国家开放大学电大《高级英语阅读(1)》《电气传动与调速系统》网络课形考网考作业(合集)答案

国家开放大学电大《高级英语阅读(1)》《电气传动与调速系统》网络课形考网考作业(合集)答案 《高级英语阅读(1)》网络课答案 形考任务一（70分）
Chapter 1 Exercise（分值7分）
题目1 I. Vocabulary skills（3 points）
Look at the columns below. Match each vocabulary word on the right with the correct definition on the left. (0.5 points each) 1.the bus or subway 2.proof of completion of courses of students 3.money for students from scholarships, grants, or loans 4.formal talks by professors or instructors on subjects of study 5.courses by video, video conferencing, or computers to students in different places 6.the points or grade a student gets on a test 答案：
II. Reading Comprehension (4 points) Read the passages, then answer the questions that follow. (1 point each ) Experiencing Culture Shock A When Eliza James arrived at the University of Xian, she was excited to live in a new country, to improve her Chinese, and to experience a culture so different from her own. But soon her excitement turned to frustration as she encountered one roadblock after another. “I felt like I couldn＇t accomplish anything. My dorm room had no heat, I couldn＇t get into the classes I wanted, and every time I asked someone for help they gave me the runaround. I felt like no one was listening to me.“ Eliza met with administrators, sent letters of complaint, and even contacted the consulate in Beijing, but she got nowhere. What Eliza didn＇t realize was that her American approach to solving problems was very different from the Chinese one in which patience and negotiation skills are key. She soon learned how to solve problems within the cultural norms of Chinese society instead of forcing her own values onto those around her. “I finally feel like I fit in and that I know what I＇m doing. In fact, it＇s really fun being in a place that＇s so incredibly different from what I am accustomed to.“ B Yoshi Yamamoto is a junior at a small college outside of Boston. Although he is an honors student now, Yoshi didn＇t always have such an easy time studying in America. “Teaching methods are very different here than they are in Japan. It took me a long time to get used to learning in seminars and discussing ideas with my classmates. At first it seemed like I wasn＇t actually learning anything.“ Yoshi＇s reaction was to totally withdraw: he didn＇t participate in class discussion; he spent lots of time alone in his room, and he even skipped class on occasion. “I thought I could teach myself. Now I recognize the value of the U.S. academic system, and I am able to adapt it to my own learning style.“ C Both Eliza and Yoshi experienced what is called culture shock: psychological disorientation due to living in a new culture. For many international students, studying abroad can offer exposure to new cultures and an opportunity to study new fields and languages. However, it also offers the greater challenge of trying to function in a foreign culture. Studying and reading about a certain culture is poor preparation for the reality of living in it. According to psychological studies, the four stages of culture shock are 1. euphoria, 2. hostility, 3. gradual adjustment, and 4. adaptation. Culture shock can be manifested in many ways: homesickness, boredom, stereotyping of or hostility towards the host culture, overeating or overdrinking, withdrawal, and inability to work effectively. D Different people experience different levels of culture shock and react in different ways. For example, Eliza got angry while Yoshi withdrew from society. The most important thing to remember is that culture shock is normal; it is not something to be ashamed of. Luckily, there are some things international students can do to make their adjustment to a new country go more smoothly. For instance, they can stay in touch with family and friends from home, join international student organizations, meet people from their own countries, and get involved in campus activities. Most importantly, they can adjust to life abroad by keeping a sense of humor and trying to remain positive. Recognizing Paragraph Topics（choose the paragraph letter）
题目2 7. an explanation of culture shock 选择一项：
A. A B. B C. C D. D 题目3 8. ways that students can adjust to living in a new country 选择一项：
A. A B. B C. C D. D 题目4 9. the experience of an international student in the United States 选择一项：
A. A B. B C. C D. D 题目5 10. the experience of an international student in China 选择一项：
A. A B. B C. C D. D Chapter 2 Exercise（分值7分）
题目1 I. Vocabulary Skills（2 points）
Sometimes examples can explain the meaning of a word or phrase. For example, sun, rain, and wind are examples of kinds of weather. Look at the columns below. Match each vocabulary word or phrase in the first column with the examples in the second column. (0.4 points each) 1.kinds of extreme weather 2.Earth’s natural materials and gases 3. diseases or health disorders 4. seasons of the year 5. natural areas or regions of the earth 答案：
II. Reading Comprehension (5 points) Complete the following statements by choosing the best from the answers A, B or C. (1 point each) Seasonal Affective Disorder: More than Just the Blues A Joshua dreads the winter months, not only because of the cold New England weather--the sleet, snow, wind, and rain--but because as the seasons change from summer to fall to winter, the days get shorter. As the days get shorter, he starts feeling depressed and irritable and spends more and more time at home, eating and sleeping. A graduate student in philosophy, Joshua finds that he gets little work done during the winter months and has trouble paying attention in class and concentrating on his research. “I soon realized that what I thought was just the ＇winter blues＇ was something more extreme than that.“ Josh visited a doctor who diagnosed him with SAD. B Seasonal Affective Disorder, or SAD, is a kind of depression that occurs seasonally. It is associated with the long hours of darkness and lack of sunlight during the winter months (people with SAD usually feel worse from December through February). Scientists don＇t completely understand the exact causes of SAD, but they believe it is related to a biochemical imbalance in the hypothalamus. The hypothalamus is the basic part of the brain that controls the body＇s breathing, heartbeat, metabolism, and hormone release. The effects of SAD include moodiness, irritability, low energy, increased appetite for carbohydrates (foods such as potatoes, rice, and bread), difficulty concentrating, and the tendency to oversleep. C Although doctors described SAD for the first time in 1984, humans have probably dealt with the disorder for thousands of years. It is not a coincidence that many cultures have important celebrations during the short days of the winter months. Christmas, Hanukkah, and Winter Solstice celebrations all occur in December. These celebrations involve lighting candles in order to bring light, warmth, and happiness to an otherwise depressing time of year. D So what can SAD sufferers do to feel better? Naturally, they need more light. For people who have mild cases of SAD, exercising in the morning sun could be enough to help them. Phototherapy, or light therapy, is usually prescribed for people who have more serious cases of the disorder. In light therapy, patients sit in front of a light box, a strong artificial light, for up to four hours a day. Phototherapy is effective in over 80% of SAD cases, and patients usually see results within three to four days. Although the symptoms of SAD are similar to those of clinical depression, traditional antidepressants have not proven useful in treating SAD. While psychological counseling cannot treat the symptoms of SAD, it is recommended to help SAD sufferers learn to accept and deal with their illness. 题目2 6. Joshua starts feeling depressed and irritable in the winter because 选择一项：
A. he gets little work done B. he suffers from Seasonal Affective Disorder C. he is a graduate student in philosophy 题目3 7. Seasonal Affective Disorder, or SAD, is a condition that researchers believe affects people during the winter months. Scientists believe it is caused by 选择一项：
A. breathing, heartbeat, metabolism, and hormone release B. moodiness, irritability, loss of energy, increased appetite, difficulty concentrating, and sleepiness C. lack of sunlight and a biochemical imbalance in the brain 题目4 8. Humans have probably struggled with SAD since 选择一项：
A. ancient times B. December C. 1984 题目5 9. People who suffer from SAD can to feel better. 选择一项：
A. do light therapy B. take antidepressant drugs C. eat carbohydrates 题目6 10. This passage talks about_____. 选择一项：
A. what the SAD effects are B. Both A and B. C. how to help SAD suffers Chapter 3 Exercise（分值7分）
I. Reading Comprehension (5 points) Read the passages, then answer the questions that follow. (1 point each ) Fast food can be good food Many people are too busy to prepare and eat three nutritious meals a day.so they turn to the convenience of fast-food restaurants. Many of the items at fast-food restaurants, snack bars, and food stands are fattening and not very nutritious.But fast food doesn’t have to be unhealthy.you can eat at fast-food restaurants and still eat well. Pay Attention to Calories and Fat Content By paying attention to the number of calories and fat that a food item has ,you can make smarter choices.Calories are “units for measuring how much energy a food will produce”.condsider two fast-food meals. A quarter-pound hamburger with cheese, jumbo-size fries,and a 16-ounce soda have a total of 1,535 calories and 76 grams of fat .a broiled (cooked under direct heat or over a flame )chicken sandwich ,a side salad with low-fat dressing,and a glass of water at the same fast-food restaurant have only 422 calories and 7 grams of fat .but maybe you really want a hamburger and fries .well,you can have a small hamburger,a small serving of fries,and a glass of water.At a total of 490 calories and 20 grams of fat,that’s still a much smarter choice than the large burger ,fries,and 20 grams of fat ,that’s still a much smarter choice than the large burger,fries,and sada. There’s More That You Can Do There are a few additional things you can do to make sure you eat well in fast food restaurantS.First of all,say “no” when the cashier asks you if you want to “supersize” you meal (order an extra large portion of each item).Second, ask for no mayonnaise or sauce,or ask for it on the side (in a separate dish).Third,substitute(use something instead of something else)healthy foods for fatty ones. For example,instead of ordering deep-fried tempura,order fresh vegetables.Instead of ordering a beef burrito with lots of cheese and sour cream,order a vegetable burrito with beans and rice.and don’t eat the chips!Another thing you can do is order a side salad or a vegetable soup and eat it first.That way,you will eat some vegetables,and you won’t be able to eat as much of your burger and fries.Fnally,eat slowly and stop eating when you’re full. It sounds simple,but many people keep eating even after they become full. 题目1 1.What is the main idea of this article ?________ 选择一项：
A. It’s smart to eat foods with low calories and fat content. B. Fast food is always bad for you . C. You can eat well in fast-food restaurant D. Fast-food restaurants are the best the place to find healthy foods . 题目2 2.A small hamburger and small firies has __________ 选择一项：
A. more calories and fat than a chicken sandwich and a salad. B. the same amount of calories and fat as a chicken sandwich and a salad. C. fewer calories and fat than a chicken sandwich and a salad. D. the same amount of calories and fat as a large portion of fries. 题目3 3.Some things you can do to eat well in fast-food restaurants are________ 选择一项：
A. ask for eatra manyonnaise and sauce and say no to “surpersizing” . B. order a vegetable burrito instead of chips and eat sour cream . C. order smaller portions and eat all the food you order. D. order healthy foods instead of fatty ones and drink water. 题目4 4.Manyonnaise and sauces probably_________ 选择一项：
A. make you eat less because they make you feel full sooner. B. make you eat more because they make your food taste better. C. have a lot of fat and calories. D. don’t have a lot of fat and calories. 题目5 5. By eating a salad or soup before the rest of your meal,_______ 选择一项：
A. you eat less of the rest of your meal. B. you eat more slowly. C. you get full sooner. D. you eat the rest of your meal more quickly. II. Vocabulary skills（2 points）
Read the paragraph below and fill in each blank with a word from the box. (0.4 points each) 题目6 changes damaging losing global available The growing similarities in diet and eating habits around the world are influencing people of various cultures in different ways. For example, Western foods are 6 damaging health in the industrialized island country of Japan. Instead of small meals of seafood, rice, and vegetables, the typical Japanese diet now includes large amounts of meat, dairy products, and desserts like tiramisu, a rich Italian dish full of chocolate, cheese, and sugar. According to Japanese health researchers, such 7 changes in eating habits are related to a great increase in health problems such as heart disease, strokes, cancer, and diabetes. On the other hand, the changing 8 global diet is having the opposite effect on the people in the CzechRepublic. The government of this European nation no longer supports meat and dairy products financially, so the cost of these foods is going up. In contrast, fresh fruits and vegetables are becoming more widely 9 available from private markets and stands. Cooks are even serving salads to schoolchildren, and families are eating healthier home-cooked meals. For these reasons, fewer Czech men are having heart attacks, the women are 10 losing a lot of weight, and most people are living healthier lives. Chapter 4 Exercise（分值7分 I. Vocabulary Skills（2 points）
题目1 Match each vocabulary word on the left with the correct definition on the right. (0.4 points each) 1.make sense 2.pedestrians 3.vehicle 4.teenager 5.fine 答案：
II. Reading Comprehension (5 points) Complete the following statements by choosing the best from the answers A, B, C, or D. (1 point each) These days, it’s getting easier and easier to find your way around. Some people have GPS devices in their cars to make sure they don’t get lost. GPS stands for Global Positioning System. These devices use satellites in space to “see” where you are and give you directions to where you want to go. And if you don’t have a GPS device, you can simply go online to get step-by-step directions. Websites like MapQuest.com and mappoint.msn.com can produce a map and directions in just a few seconds. But how do they do it? MapQuest® uses data (information) from a few different sources to produce directions and maps. Before MapQuest® went online, it sold regular paper maps in places like gas stations. The website uses the data from those paper maps, information from digital mapping companies, and government databases. At the moment, MapQuest® uses more than 30 computers to read all this data and provides users with millions of maps every day. In order to find the best route (way or path) from one place to another, MapQuest® first has to look at all possible routes. Then MapQuest® looks at each part of each possible route. It considers the types of roads on the different routes. Are they dirt roads, paved roads, freeways, or city streets? It looks at how many turns there are in each route and what kinds of turns they are. Are they right turns or left turns? It also considers the speed limit on each road and how many intersections there are. An intersection is “a place where two or more roads cross each other”. MapQuest® can also tell you how long your trip will take you. It does this by doing some math. MapQuest® bases its estimated driving times on the length and speed limit of each part of the route and the amount of time it probably takes to get through each intersection. For example, it allows more time for a left turn at an intersection than it does for a right turn. Someday, maybe we will have cars that can just drive us wherever we want to go, but for now, mapping websites make it a little harder to get lost. 题目2 6.What is the main idea of this article? 选择一项：
A. Why mapping websites don’t work well. B. Why mapping websites are better than paper maps. C. How mapping websites work. D. How the first mapping website started. 题目3 7.According to the article, MapQuest®______ 选择一项：
A. started as maker of government databases. B. started as an Internet company. C. uses millions of computers to read data. D. starting by selling paper maps. 题目4 8.When you search for directions, the first thing MapQuest® does is_______ 选择一项：
A. consider how many turns you want to take. B. print out a map and directions. C. estimate driving time. D. look at all possible paths. 题目5 9.When it’s deciding on the best route, MapQuest® probably chooses ________ 选择一项：
A. the route with the most turns. B. dirt roads instead of paved roads. C. freeways instead of dirt roads. D. city streets instead of freeways. 题目6 10. To estimate your driving time, MapQuest® considers _________ 选择一项：
A. the distance between turns on your route. B. the speed limit for half of the route. C. the fastest and slowest speed limits on your route. D. the speed limits and types of turns on your route. Chapter 5 Exercise（分值7分）
I. Reading Comprehension (5 points) Read the five main-idea questions that follow about the information in the reading. Three details correctly answer each question. Cross out the untrue, unrelated detail. (1 point each ) 题目1 1. What are the definitions of the two main types of families? 选择一项：
A. Human beings lived in loosely-related groups. Each group had a common ancestor long time ago. B. The nuclear family consists of two parents and their biological or adopted children. C. The extended family may include grandparents, parents, children and relatives living together on the same street or in the same area. D. The nuclear family is the same as the extended family. 题目2 2. What are the reasons for the changes in the structure of the family? 选择一项：
A. The divorce rate went down and the birthrate began to rise in the early 1900s in the United States. B. Couples did not want many children then. C. In the early 1900s in the United States, the divorce rated went down and the birthrate went down. D. At that time, couples were staying married for few years. 题目3 3. What happened to families in industrialized countries in the 1930s and 1940s? 选择一项：
A. Before and during World War II, families faced few financial problems and women didn’t have to work away from home. B. Men were at war, so women had to work outside the home. C. Before and during World War II, families had problems. D. Families had serious financial problems during World War II. 题目4 4. What changes will happen to family structure during the next decades? 选择一项：
A. Divorces would be fewer, mothers would stay at home after the war. B. Children began living at home longer. C. After the war, family structure changed back. D. After the war, there were more divorces and fewer stay-home-mothers. 题目5 5. What will families be like in the future? 选择一项：
A. Many people want the traditional two-parent family back. B. Two-parent family will probably come back and all other family forms will end. C. Unmarried parents with adopted or foster children, and one-person households. D. There may be more single-parent families. II. Vocabulary Skills（2 points）
Read the paragraph below and fill in each blank with a word from the box. ( 0.4 points each) 题目6 living extended category typical believe The Family of the Future Many people today would like the traditional two-parent family back—that is to say, they want a man and a woman to marry for life; they also think the man should sport the family and the woman should stay home with the children. However, few families now fall into this 6 category In fact, if more women decide to have children on their own, the single-parent household may become more 7 typical than the traditional family in many countries. Also, unmarried couples may decided to have more children—or they might take in foster children or adopt. And because people are staying single and 8 living longer (often as widows), there may be more one-person households in the future. On the other hand, some people 9 believe similar events happen again and again in history. If this is true, people may go back to the traditional 10 extended or nuclear family of the past. Others think the only certainty in history is changing: in other words, the structure of the future family could begin to change faster and faster—and in more and more ways. Chapter 6 Exercise（分值7分）
I. Vocabulary skills（2 points）
Complete the following statements by choosing the best from the answers A, B, C, or D. （0.4 points each）
题目1 1. Some examples of the architecture of old Europe are the magnificent cathedrals and castles. The design and building styles of modern architecture are excellent too. What does the noun architecture mean in these sentences? 选择一项：
A. the place with significant civilization everywhere B. people that study the culture of old Europe and other societies C. the art and science of designing the study of classical literature D. the form and plan of buildings and other structures 题目2 2. Perhaps the real beginning of civilization—with its scientific and technological discoveries and inventions—was in the Middle East and Africa. Over five thousand years ago, those ancient civilizations had astronomy, mathematics, medicine, government, and so on. Which word is a synonym of the word civilization? 选择一项：
A. technology B. cathedral C. culture D. astronomy 题目3 3. The cultural legacy of ancient Chinese and Indian peoples included walled cities, the first governments, tools for work, and weapons for protection. odern peoples built on this legacy.What is a possible explanation of the word legacy? 选择一项：
A. ideas and achievements passed from earlier generations to modern society B. a gift of money that somebody gives to another person C. international business conducted in cities and government structures D. the state or condition of being legal; not against the law 题目4 4. “For me, the idea of ancient culture creates a contradiction in definitions,” said Karen, going against Mei’s views. “Only modern things can be part of culture.Of course, people that like classical art and music will contradict me.” What might the noun contradiction mean? 选择一项：
A. the opposition of two opinions B. wearing a Hawaiian shirt in an ancient culture C. the short forms of two words together D. to put words together 题目5 5. Because of the worldwide media—movies, TV, CDs, the Internet, newspapers, magazines—everybody knows the same information, plays the same music, and enjoys the same jokes.How might you define the phrase the media? 选择一项：
A. the combination of visual, sound, and printed ways to send ideas around the world B. communication styles include motions, gestures and facial expressions C. the tradition of being in the middle—not on the extremes of possible views D. events that appear in the daily news and that everyone knows about II.Reading Comprehension (5 points) Decide whether the following statements are true or false. Write “T” for True and “F” for False. （1 point each）
题目6 Many visitors to different countries don’t realize how important it is to understand a country’s culture. Sometimes people learn this lesson by making a big cross-cultural blunder, or embarrassing mistake. In business situations, these blunders can cost a lot of money or end business relationships. 6.It is important to understand other people’s cultures before you do business with them. 选择一项：
A. F B. T 题目7 For example, one company wanted to sell toothpaste in Southeast Asia. In their advertisements, they claimed that their toothpaste whitens teeth. They didn’t understand that many of the local people chewed betel nuts to make their teeth black, and that these people thought black teeth were attractive. 7. The toothpaste company probably kept using the same advertisement in Southeast Asia. 选择一项：
A. F B. T 题目8 In another case, a car company tried to sell a car called “Matador” in a Spanish-speaking country. The company thought that it was a strong name because it means “bullfighter”. In Spanish, matador is indeed a noun meaning “bullfighter”. But it is also an adjective meaning “killing”. Imagine driving around in a car called “Killing”! 8. The car company that tried to sell a car to a Spanish-speaking country probably didn’t sell many Matador cars in that country. 选择一项：
A. F B. T 题目9 A European businessman had an important meeting with a company in Taiwan. He wanted to bring gifts for the people he was meeting with. He thought that something with his company’s logo on it would be a nice gift. So he bought some very nice pocket knives and had his company’s logo printed on them. He didn’t know that giving a knife as a gift symbolizes cutting off a friendship! 9. The European businessman probably researches new cultures before he visits them now. 选择一项：
A. T B. F 题目10 It’s very easy to make blunders like these people did. But it’s also very easy not to. Before you visit a new country, research that country’s customs and etiquette (social rules for polite behavior). You can find a lot of information online. Just go to a search engine and type in key words like “cross-cultural etiquette” or “cultural information Taiwan”. By spending a few minutes doing research, you can save yourself from a lot of embarrassment and make sure you don’t accidentally offend anyone. 10. What you can disagree with people to save yourself from making cross-cultural blunders. 选择一项：
A. T B. F Chapter 7 Exercise（分值7分）
I. Reading Comprehension (5 points) Decide whether the following statements are true or false. Write “T” for True and “F” for False on the Answer Sheet. (1 point each) 题目1 For instance, a doctor doesn’t always have time to thoroughly explain an illness. In these cases, the Internet can be a valuable resource—a place to read all about the causes, symptoms, and remedies for an illness. 1. One benefit of using the Internet as a medical resource is it has a lot of information about illnesses and diseases. 选择一项：
A. F B. T 题目2 For example, some websites claim that sniffing (smelling) a newspaper can cure nausea (the feeling of being sick to your stomach and wanting to vomit). 2. One possible remedy for nausea is drinking a lot of tea. 选择一项：
A. T B. F 题目3 Other websites suggest that a person with a cold should keep a piece of raw garlic in his or her mouth all day and bite down on it every few minutes to release the juice. People with smelly feet are told to soak their feet in tea for half an hour. 3. The websites remedies might be unpleasant or odd, but they probably will cause harm. And who knows? They might actually be unhelpful. 选择一项：
A. F B. T 题目4 An herbal remedy for helping your memory may also be a blood thinner. So if your doctor prescribed (put you on) a blood thinner and you start taking this herb without asking your doctor about it, a simple cut could be deadly; you might not be able to stop bleeding. 4. A person who is taking a prescribed drug should probably talk to the doctor before taking an herbal remedy. 选择一项：
A. F B. T 题目5 The bottom line is this: be careful when using the Internet as a health resource. Use it to find information that you can discuss with your doctor. But don’t spend a lot of money on “miracle cures”. 5. The best way to use the Internet as a medical resource is to read about your illness and discuss what you find out with your doctor. 选择一项：
A. T B. F II. Vocabulary skills（2 points）
Read the paragraph below and fill in each blank with a word from the box. ( 0.4 points each) 题目6 disease substance classification prevent figure In a small-town farm market, hundreds of elderly people drink a glass of sour dark cherry juice every day. These happy senior citizens, some of them over the age of 90, claim that the natural fruit juice cures—or at least decreases—the pain of their arthritis, a 6 disease of the joints of the aging body. It’s a folk remedy, not a proven medical therapy. Nevertheless, science is beginning to 7 figure out why sour cherry juice might work to improve the health of patients with arthritis. The secret is in the 8 substance that gives the cherries their dark red color. It belongs to a 9 classification of natural nutrients that color blueberries, strawberries, plums, and other fruits—and vegetables too. Moreover, these coloring substances may help to 10 prevent serious health disorders like heart disease and cancer. In other words, vitamins and fiber are not the only reasons to eat fruits and vegetables. “To take advantage of natural whole foods,” advise nutritionists. Chapter 8 Exercise（分值7分）
I. Vocabulary Skills（2 points）
Complete the following statements by choosing the best from the answers A, B, C, or D. ( 0.4 points each) 题目1 1.At all hours, the media offer language learners “real-life” audio visual instruction and practice in aural comprehension. 选择一项：
A. hospital and health information B. understanding spoken language C. the answers to test questions D. real-life experience 题目2 2. High-quality TV programming —a good plan of shows about various fields of study—can increase people’s knowledge and improve their thinking abilities. 选择一项：
A. scientific and medical shows B. movies with good music C. academic lecture courses D. choice and organization of shows 题目3 3. Television and video provide almost everyone with good entertainment—a pleasant way to relax and spend free time at home. 选择一项：
A. amusement or pleasure B. freedom from worry and tension C. relaxation through exercise D. fun through serious study 题目4 4. Images of violence on the screen scare people, giving them terrible nightmares when they sleep. 选择一项：
A. dark, stormy weather B. bad conditions C. physical disabilities D. behavior that hurts people 题目5 5. The talk shows of “trash TV” make instant “stars” of real people with strange or immoral ideas, who tell their most personal secrets, shout angrily, and attack one another. 选择一项：
A. valuable programs B. negative effects C. shows without quality D. normal life stories II. Reading Comprehension (5 points) Complete the following sentences by choosing the best from the answers A, B, C, or D. (1 point each) A Everyone makes mistakes, or so the saying goes. But have you ever heard about mistakes in Hollywood? When most people think of Hollywood, they think of blockbusters (very successful movies), high-paid actors, glitz, and glamour. But according to one Website, many Hollywood movies are full of mistakes. Some are technical errors. For instance, in a scene of the science-fiction adventure film The Matrix, when the main character steps out of his car, the viewer can clearly see the camera crew in the car window. In another scene, the same character is typing on his computer, yet the computer screen is blank. Other movie mistakes are historical. For example, the epic Gladiator, an Oscar winner, is known for having lots of historical errors. Throughout the movie, the gladiator Maximus refers to his home in Spain, and the other characters call him “the Spaniard.“ However, in 180 A.D., when the movie takes place, Spain as a country or even as a concept didn＇t exist yet. At another point in the movie, Maximus says that his homeland of Spain has “the best horses.“ But horses weren＇t brought to the Iberian Peninsula until the invasion of the Moors (North Africans) in 711 A.D, more than 500 years after the movie takes place. The historical drama Titanic, another Oscar winner, also has its share of historical blunders. The Titanic sunk in the year 1912. So why is one of the characters wearing a digital watch? In fact, movie watchers have found over 100 mistakes in The Matrix, Gladiator, and Titanic. Can you think of any errors in your favorite films? B How susceptible are you to advertising? Has a TV commercial or magazine ad ever made you buy the product that was advertised? If so, perhaps you have been subjected to subliminal advertising. Subliminal advertising is a kind of advertising that appeals to the subconscious. The word “subliminal“ comes from the Latin “sub“ meaning “lower,“ “beneath,“ or “under,“ and “limen“ meaning “threshold,“ (the level at which something begins to happen). Thus, subliminal advertising stimulates your brain at a level below conscious perception. You cannot see, hear, or perceive subliminal ads, but they may affect you just the same. There are two main types of subliminal ads. The first involves flashing messages quickly during a commercial or film. The messages appear and disappear so rapidly that the mind cannot process them consciously, but it might receive them passively, at a subconscious level. James Vicary, a market researcher, first introduced this kind of subliminal advertising in 1957 when he flashed the words “Eat Popcorn“ and “Drink Coca-Cola“ every five seconds during a movie. The messages couldn＇t be seen, yet Vicary claimed that the moviegoers＇ brains could perceive them: Coke sales went up by 18% and popcorn sales by over 50%. More recently, the same type of subliminal advertising was used in a negative ad for a political campaign. In the ad, the word “rats“ flashed up briefly during the part of the ad describing one party＇s healthcare plan. The purpose was to associate that opposing party with the negative word “rats.“ The second kind of subliminal advertising involves hiding or incorporating images into visual advertisements. A well-known example is on a package of a famous brand of cigarettes. Some say that if you look closely you can see the image of a man who is sexually aroused. In fact, a lot of subliminal advertising involves sex, coming from the idea that “sex sells.“ One media researcher claims that everything from crackers to alcohol to soda has used subliminal sexual imagery to appeal to buyers. Although studies show that consumers believe strongly in the power of subliminal ads, no one can prove the effects of subliminal advertising. Psychologists and others who study subliminal stimuli have not been able to show that subliminal advertising actually works. Many advertising researchers believe that traditional ads, in which a powerful image is used to sell a product, are more effective than subliminal advertising. All the same, it still remains a controversial topic, one that is on the mind of buyers and sellers alike. 题目6 6. What is the best title for the Paragraph A? 选择一项：
A. The Success of Hollywood: Movie Madness. B. Hollywood Bloopers: Mega Movie Mistakes. C. History or Hollywood? Hollywood Interprets Famous Historical Events. 题目7 7. What is the best title for the Paragraph B? 选择一项：
A. The Effect of Advertising on the Human Brain. B. Sex Sells: This History of Sex in Advertising. C. Subliminal Advertising: What Is It? Does It Work? 题目8 8.The Moors invaded Spain ______ the movie Gladiator takes place. 选择一项：
A. before B. after C. since 题目9 9. Another word for mistake is ______. 选择一项：
A. error B. blunder C. A and B 题目10 10.The subconscious is the part of the brain that _______. 选择一项：
A. passively notices and remembers information B. actively notices and remembers information C. does not notice or remember information Chapter 9 Exercise（分值7分）
I. Vocabulary Skills（2 points）
题目1 Which of the words below contain a prefix with a negative meaning? Choose N. Choose X for the words without negative meanings. ( 0.4 points each) discourage 答案 N disrespect 答案 N illustrate 答案 X instant 答案 X illegal 答案 N II. Reading Comprehension (5 points) Complete the following statements by choosing the best from the answers A, B, C, or D. (1 point each) Meeting the Perfect Mate What is the best way to meet the perfect husband or wife? I am continuing to interview students on campus trying to answer this question for my sociology class. So far, people have mentioned arranged matches, discos and bars, computer dating services, and personal ads. One guy even said he thought supermarkets were the best places to meet women. I guess you can talk a lot about a head of lettuce! I decided to go to the school cafeteria to interview some people there. “I think date cafés are the best way to meet people,“ said my friend Rahul. “Date cafés? What＇s that?“ I asked. “Well, a date café is both a café and a dating service. You go to the café, order a cup of coffee or whatever you want, and look through people＇s profiles. Then, if someone interests you, you can send him or her an email and arrange a date at the café. You can also fill out your own profile and have people email you. The form asks you about everything from looks, to interests, to religion. The date café is a relaxed way to make contacts.“ “Are there many of them around?“ I asked. “Hmm. Well, there＇s one near campus called Drip. In fact, I had a Drip date just last week,“ said Rahul. “Drip! But isn＇t that a word that＇s used to describe someone who is dull and boring? It doesn＇t sound too promising.“ “Yeah, well it＇s funny you say that, because my date was pretty uninteresting. She barely talked at all, and she kept looking down at her coffee mug.“ “Well, what about a mail order bride?“ said Rahul＇s roommate, Joni. “A what?“ I asked. “A mail order bride. You know, you search for your wife in a catalog and the next thing you know you＇re married. With the Internet it＇s easier than ever,“ she said. “Ugh, that sounds awful.“ I said. “Have you ever met anyone who has done that?“ “Yes, my uncle did it. His marriage ended a year later. The truth is, I＇m against it. Usually the women come from poor countries and don＇t know what they＇re getting into. My uncle＇s wife had a really hard time adjusting and went back to her country as soon as they split up.“ “I think mail order is out. Any other suggestions?“ “I find that meeting people through classes or extracurricular activities is a good idea,“ said Michelle. “For instance, I signed up for a Japanese cooking class, both because I like Japanese food, and because I thought I might meet someone nice with similar interests.“ “And did you?“ “Yeah, I made lots of friends: Sumi, Katrina, Mariah...no guys, though. The class was 90% women. In fact, now that you mention it, the same thing happened with the salsa class, the pottery class and my Tai Chi class. I met a lot of nice women, but I definitely did not find the man of my dreams.“ Last I interviewed a couple in the library. “Friends“ they said. “We met through friends. It＇s the best way to find the perfect mate.“ “Really,“ I said. “And why is that?“ “Well, your friends usually know what you like. And also, you know the person is someone you can trust, not like meeting someone in a bar or a supermarket. For instance, we met because Chris＇s lab partner thought we would really get along.“ “Yeah, Scott and I met, and I immediately liked him. I emailed him and it took him three months to email me back!“ “Well, I＇m a little shy, but it eventually worked. Here we are, a year later and still together.“ “Well that＇s the best story I＇ve heard yet, “ I said. But if I＇ve learned one thing in this study, it＇s that meeting someone special, no matter how you do it, is difficult.“ 题目2 6.If you interview someone, you __. 选择一项：
A. ask him/her a lot of questions B. ask him/her to fill out a form 题目3 7. A person＇s profile probably __. 选择一项：
A. shows a picture of the person B. tells something about the person 题目4 8. A drip is __. 选择一项：
A. a kind of computer dating service B. a dull, boring person 题目5 9. If something is awful, it＇s __. 选择一项：
A. interesting and unusual B. unpleasant and bad 题目6 10. If you and your mate split up, you __. 选择一项：
A. end your relationship B. get engaged Chapter 10 Exercise（分值7分）
I. Reading Comprehension (5 points) Decide whether the following statements are true or false. Choose “T” for True and “F” for False. (1 point each ) 题目1 Competition in Olympic sports is supposed to be fair. However, in judged sports, fairness is impossible. Therefore, judged sports should be banned from the Olympic games. A judged sport is any sport that requires judges to determine a winner. For example, gymnastics, figure skating, half pipe (snowboarding), and diving are all judged sports. 1.The writer believes judged sports should be eliminated from the Olympics. 选择一项：
A. T B. F 题目2 Why do I believe that judged sports should be eliminated from the Olympics? First of all, judges don’t see everything. For example, a mistake in figure skating can happen in a fraction of a second. If a judge blinks or looks away for a moment, he or she might miss the mistake and give the skater a higher score than the skater deserves. 2.One reason that judged sports should not be allowed in the Olympics is that judges can have different opinions. 选择一项：
A. T B. F 题目3 Second, two judges can disagree about which athlete gave the best performance. In sports in which the difference between gold and silver is usually a few hundredths of a point, this kind of subjectivity is unacceptable. Can anyone really say with certainty that a gymnast who receives a score of 9.825 is a better gymnast than one who scores 9.823? 3.One argument against banning judged sports from the Olympics is that people should stop arguing about it. 选择一项：
A. T B. F 题目4 A lot of people claim that judged sports are subjective and should not be allowed in the Olympics. They feel that only sports that are measured objectively for things like speed, such as swimming, track, and skiing, should be allowed because judges can’t be objective and fair. I disagree with these people. Why? I believe that no sport is 100% fair and objective. 4. The writer here believes all sports are objective. 选择一项：
A. T B. F 题目5 Some athletes may win because their equipment is better than their opponents’ equipment. For example, in the 2000 summer Olympics, some swimmers wore controversial high-tech suits. The maker of the suit claimed that the fabric could make a swimmer 3% faster. No one could prove that this was true, but they couldn’t prove that it wasn’t true either. 5. The equipment can be one reason that decides athletes’ sports scores. 选择一项：
A. T B. F 题目6 II. Vocabulary Skills（2 points）
Match the following vocabulary items on left with their possible explanations on right. ( 0.4 points each) co-worker contribute promotion progress intermission 答案：
形考任务二（30分）
破冰行动（所属章：Guidelines；
分值5分；
需要教师批阅）讨论区 异国特色食谱（所属章：Chapter 3；
分值5分；
需要教师批阅）讨论区 身边的家庭模式（所属章：Chapter 5；
分值5分；
需要教师批阅）讨论区 新闻采访稿（所属章：Chapter 8；
分值5分；
需要教师批阅）互动评价 网上表现（所属章：所有章节；
分值10分；
需要教师批阅）
《电气传动与调速系统》网络课答案 形考任务1 一、选择题（每小题5分，共40分）
题目1 电气传动系统做旋转运动时，其运动方程为（ ）。

选择一项：
题目2 如图所示的旋转运动系统（箭头方向表示转矩的实际方向），系统的运动状态是（ ）。

选择一项：
A. 匀速 B. 加速 C. 静止 D. 减速 题目3 如图所示的负载机械特性属于（ ）。

选择一项：
A. 恒功率负载机械特性 B. 位能性恒转矩负载机械特性 C. 反抗性恒转矩负载机械特性 D. 直线型负载机械特性 题目4 如图所示的电动机机械特性（曲线1）与负载机械特性（曲线2）相交的交点分别为A和B，以下说法正确的是（ ）。

选择一项：
A. A点是稳定运行点，B点是稳定运行点 B. A点是稳定运行点，B点不是稳定运行点 C. A点不是稳定运行点，B点不是稳定运行点 D. A点不是稳定运行点，B点是稳定运行点 题目5 直流电动机的换向器与电刷配合，可将电枢绕组内的（ ）变换为电刷上的直流电势。

选择一项：
A. 交流电势 B. 直流电势 C. 恒定电压 D. 不变电势 题目6 如图所示为他励直流电动机的机械特性曲线组，表示的是（ ）的人为机械特性。

选择一项：
A. 减弱磁通 B. 降低电源电压 C. 电枢回路串电阻 D. 增大磁通 题目7 如图所示为他励直流电动机的工作特性曲线，下述表达正确的是（ ）。

选择一项：
A. 曲线1是转速特性，曲线2是效率特性，曲线3是转矩特性 B. 曲线1是转矩特性，曲线2是效率特性，曲线3是转速特性 C. 曲线1是效率特性，曲线2是转速特性，曲线3是转矩特性 D. 曲线1是转速特性，曲线2是转矩特性，曲线3是效率特性 题目8 如图所示他励直流电动机机械特性与负载机械特性曲线的交点a,b,c,d，下述表达正确的是（ ）。

选择一项：
A. 从a点到b点是属于调速运行，从c点到d点属于调速运行 B. 从a点到c点是属于调速运行，从c点到d点属于调速运行 C. 从a点到c点是属于调速运行，从b点到d点属于调速运行 D. 从a点到b点是属于调速运行，从b点到d点属于调速运行 二、判断题（每小题5分，共40分）
题目9 当传动系统做旋转运动时，作用在电动机轴上的电磁转矩T和负载转矩TL之差，即T-TL=△T称为动态转矩，当△T>0，即dn/dt > 0时，系统处于加速运行状态。

（ ）
选择一项：
对 错 题目10 如图所示的负载机械特性属于恒功率负载机械特性。（ ）
选择一项：
对 错 题目11 如图所示的电动机机械特性（曲线1）与负载机械特性（曲线2）相交的交点分别为C、D和E，则C点不是稳定运行点，D点是不稳定运行点, E点是稳定运行点。（ ）。

选择一项：
对 错 题目12 直流电机的主磁极是产生电动势的部件。（ ）
选择一项：
对 错 题目13 直流电动机工作时，其电枢绕组中的电流是交流电流。（ ）
选择一项：
对 错 题目14 直流电动机的转速大小与励磁电流大小、电枢回路电阻值和所加电源电压的极性有关。

选择一项：
对 错 题目15 如图所示为他励直流电动机的机械特性曲线组，表示的是电枢回路串电阻的人为机械特性。（ ）
选择一项：
对 错 题目16 如图所示为他励直流电动机四象限运行的机械特性曲线，曲线1是正向电动运行状态，曲线2是能耗制动运行状态，曲线3是反向电动运行状态。（ ）
选择一项：
对 错 三、综合题（每小题10分，共20分）
某刨床电气传动系统如图1-6所示。已知切削力F=10000N，工作台与工件运动速度（），传动机构总效率（），电动机转速（），电动机的飞轮矩（）。

题目17 切削时折算到电动机轴上的负载转矩为（ ）
选择一项：
A. 40Nm B. 50Nm C. 41.2Nm D. 30Nm 题目18 取，估算系统的总飞轮矩为（ ）
选择一项：
A. 120Nm2 B. 110Nm2 C. 130Nm2 D. 100Nm2 一台他励直流电动机的额定数据为：PN = 30 kW，UN= 220 V，IN=156.9 A，nN=1500 r/min，Ra= 0.082Ω。

题目19 电动机的理想空载转速为（ ）。

选择一项：
A. 1494r/min B. 1594r/min C. 1394r/min D. 1694r/min 题目20 电动机的额定电磁转矩为（ ）。

选择一项：
A. 406.8Nm B. 306.8Nm C. 206.8Nm D. 106.8Nm 形考任务2 一、选择题（每小题5分，共40分）
题目1 三相异步电动机正常运行时，转子转速为n，定子旋转磁场的转速为ns，则该电动机的转差率s为（ ）。

选择一项：
题目2 一台6极三相异步电动机，定子电流频率为60Hz，电机正常运行时，定子旋转磁场的转速为（ ）。

选择一项：
A. 1000r/min B. 1200r/min C. 600r/min D. 500r/min 题目3 一台8极三相异步电动机，定子电流频率为50Hz，电机正常运行时的转差率s为0.04，则该电机正常运行时转子电流的频率为（ ）。

选择一项：
A. 48 Hz B. 50 Hz C. 1.5 Hz D. 2 Hz 题目4 三相异步电动机的T型等效电路如图所示，m1表示电机的相数，则定子绕组的铜耗可表示为（ ）。

选择一项：
题目5 三相异步电动机的固有机械特性如图所示，则A点是（ ）。

选择一项：
A. 同步转速点 B. 额定运行点 C. 最大转矩点 D. 起动点 题目6 三相异步电动机的人为机械特性如图所示，该图表示的是（ ）的人为机械特性。

选择一项：
A. 改变频率（基频以下）
B. 降低电源电压 C. 转子回路串电阻 D. 改变频率（基频以上）
题目7 一台同步电动机的矩角特性如图所示，可知，该同步电动机为（ ）。

选择一项：
A. 凸极同步电动机 B. 隐极同步电动机 C. 笼型同步电动机 D. 绕线式同步电动机 题目8 为了调节同步电动机从电网吸取的无功功率以及同步电动机的功率因数，需要调节同步电动机的（ ）就可以实现。

选择一项：
A. 负载的功率因数 B. 电枢电流 C. 励磁电流 D. 电枢电压 二、判断题（每小题5分，共40分）
题目9 三相异步电动机的转子绕组分为笼型转子和绕线型转子两类。

（ ）
选择一项：
对 错 题目10 一台4极三相异步电动机，定子电流频率为50Hz，电机正常运行时的转差率s为0.02，则该电机定子旋转磁场与转子之间的相对转速为30r/min。（ ）
选择一项：
对 错 题目11 三相异步电动机的人为机械特性如图所示，该图表示的是降低电源电压的人为机械特性。（ ）
选择一项：
对 错 题目12 三相异步电动机能耗制动时的机械特性不经过原点，但位于第二、四象限内。

（ ）
选择一项：
对 错 题目13 三相异步电动机的调速方法有：变极调速、变频调速和弱磁调速。

（ ）
选择一项：
对 错 题目14 隐极同步电动机的定子电压方程为。（ ）
选择一项：
对 错 题目15 凸极同步电动机的电磁转矩与功率角之间的关系（矩角特性）可表示为。（ ）
选择一项：
对 错 题目16 当同步电动机的励磁电流大于正常励磁值时，同步电动机处于过励运行状态。（ ）
选择一项：
对 错 三、综合题（每小题10分，共20分）
一台六极三相鼠笼式异步电动机，定子绕组为Y接，额定电压UN＝380V，额定转速nN＝965r/min，电源频率f1＝50Hz。

题目17 电动机的同步转速和额定转差率分别为（ ）。

选择一项：
A. 750r/min，0.045 B. 1000r/min，0.035 C. 500r/min，0.02 D. 1500r/min，0.025 题目18 电动机定子绕组的额定相电压与转子电流的频率分别为（ ）。

选择一项：
A. 150V，3.75Hz B. 110V，2.75Hz C. 380V，1.75Hz D. 220V，1.75Hz 一台六极三相鼠笼式异步电动机，定子绕组为Y接，额定电压UN＝380V，额定转速nN＝965r/min，电源频率f1＝50Hz，定子电阻r1＝2.1Ω，定子漏抗χ1＝3.08Ω，转子电阻的折算值r＇2＝1.48Ω，转子漏抗的折算值χ＇2＝4.2Ω。已知电磁转矩计算公式为 题目19 电动机的额定转差率和定子绕组的额定相电压分别为（ ）。

选择一项：
A. 0.035，220V B. 0.035，380V C. 0.045，220V D. 0.02，220V 题目20 电动机的额定电磁转矩和起动转矩分别为（ ）。

选择一项：
A. 45Nm，51.2Nm B. 25Nm，21.2Nm C. 15Nm，41.2Nm D. 35Nm，31.2Nm 形考任务3 一、选择题（每小题5分，共40分）
题目1 微型同步电动机根据转子结构型式和所用材料不同主要分为永磁式微型同步电动机、反应式微型同步电动机和（ ）。

选择一项：
A. 隐极微型同步电动机 B. 磁滞式微型同步电动机 C. 鼠笼式微型同步电动机 D. 绕线式微型同步电动机 题目2 直流伺服电动机的控制方式有：电枢控制和（ ）。

选择一项：
A. 电流控制 B. 电压控制 C. 磁场控制 D. 电阻控制 题目3 一台伺服电动机的机械特性曲线如图所示，可知，该电动机应该是（ ）。

选择一项：
A. 笼型伺服电动机 B. 直流伺服电动机 C. 永磁伺服电动机 D. 交流伺服电动机 题目4 一台伺服电动机的机械特性曲线如图所示，可知，该电动机应该是（ ）。

选择一项：
A. 直流伺服电动机 B. 永磁伺服电动机 C. 笼型伺服电动机 D. 交流伺服电动机 题目5 步进电动机也称（ ），是一种将输人脉冲信号转换成输出轴的角位移（或直线位移）的执行元件。

选择一项：
A. 永磁电动机 B. 交流电动机 C. 直流电动机 D. 脉冲电动机 题目6 电动机某部位的温度θ与电动机周围介质的温度θ0之差，称为电动机该部位的（ ），用τ表示，即τ =θ-θ0。

选择一项：
A. 温升限值 B. 最小温升 C. 温升 D. 最大温升 题目7 我国国家标准《旋转电机 定额和性能》（GB755-2008）中规定周围冷却空气的最高温度为（ ）。

选择一项：
题目8 电动机（ ）的选择，首先必须校验电动机运行时的温升，特别当传动系统中的负载是变化的，或者是冲击性负载时，还必须根据温升校核后再核验电动机的过载能力或起动能力等。

选择一项：
A. 额定功率 B. 额定电压 C. 起动电流倍数 D. 额定转速 二、判断题（每小题5分，共40分）
题目9 反应式微型同步电动机转子在不同的方向具有不同的磁阻，X轴方向磁阻最小，交轴方向磁阻最大。（ ）
选择一项：
对 错 题目10 根据自动控制系统的要求，伺服电动机必须具备可控性好、稳定性高和响应快速等基本性能。（ ）
选择一项：
对 错 题目11 交流伺服电动机的控制方式有：幅值控制、相位控制和电流控制。（ ）
选择一项：
对 错 题目12 在电机内部，当发热量等于散热量时，电机温升不再升高，逐步达到其稳定温升τw。（ ）
选择一项：
对 错 题目13 电机在发热过程中的温升曲线与在冷却过程中的冷却曲线均是按指数规律变化的，变化的快慢与发热时间常数T有关，同一物体的冷却时间常数与发热时间常数T的关系是相同的。（ ）
选择一项：
对 错 题目14 电机中常用的绝缘材料按其耐热能力可分为A、E、B、F、H、C、N和R八个等级，相应绝缘等级最高温度分别为105、120、130、155、180、200、220、240（℃）。（ ）
选择一项：
对 错 题目15 我国国家标准《旋转电机 定额和性能》（GB755-2008）中，将电动机的工作方式分为连续工作制、断续周期工作制和长时工作制。（ ）
选择一项：
对 错 题目16 在电动机的断续周期工作制中，我国国家标准《旋转电机 定额和性能》（GB755-2008）规定的负载持续率有15%、25%、40% 和60%四种，相应还规定每个工作和停机的周期不大于10min。（ ）
选择一项：
对 错 三、综合题（每小题10分，共20分）
一台三相六极反应式步进电动机，转子的齿数Z=12。

题目17 电机作三相单三拍运行时，电机的齿距角与步距角分别为（ ）。

选择一项：
A. 72o，5o B. 30o，10o C. 72o，20o D. 36o，10o 题目18 电机作三相双六拍运行时，电机的齿距角与步距角分别为（ ）。

选择一项：
A. 30o，5o B. 30o，6o C. 36o，5o D. 36o，6o 一台反应式步进电动机，已知电机运行时的拍数N=6，脉冲频率f=800。

题目19 当电机的步距角为1.2°时，转子的齿数Z为（ ）。

选择一项：
A. 20 B. 60 C. 30 D. 50 题目20 电机转子每分钟的转速为（ ）。

选择一项：
A. 150r/min B. 160r/min C. 200r/min D. 250r/min 形考任务4 一、选择题（每小题5分，共40分）
题目1 晶闸管在触发导通之后，通过以下哪种方式可以让其关断？（ ）
选择一项：
A. 门极不加电流 B. 阳极与阴极间加正压 C. 门极加电流 D. 阳极与阴极间加反压 题目2 升压DC/DC变换器在开关管导通时，负载能量由以下哪种元件提供？（ ）
选择一项：
A. 输入电源 B. 输出侧滤波电容 C. 续流二极管 D. 储能电感 题目3 保证（ ）时，异步电动机在变频调速过程中最大电磁转矩维持不变。

选择一项：
A. 恒定的端电压/频率 B. 恒定的电动势 C. 恒定的电动势/频率 D. 恒定的端电压 题目4 电压源型通用变频器在直流侧采用（ ）对整流后的电压进行滤波。

选择一项：
A. 二极管 B. 晶闸管 C. 电感 D. 电容 题目5 变频调速系统出现与机械系统的固有频率发生谐振时，需要设置（ ）。

选择一项：
A. 频率跳变 B. 下限频率 C. 起动频率 D. 上限频率 题目6 异步电动机变频调速时，减速时间设置过短会导致（ ）。

选择一项：
A. 直流侧欠电压 B. 输入侧欠电压 C. 直流侧过电压 D. 输入侧过电压 题目7 恒压变频供水系统中，变频器不需要设置（ ）。

选择一项：
A. 点动频率 B. 减速时间 C. 最高频率 D. 升速时间 题目8 一台变频器驱动多台同步电动机进行变频调速时，应采用（ ）。

选择一项：
A. 交-直-交无换向器电动机调速系统 B. 反电势换流型无换向器电动机调速系统 C. 他控式变频调速系统 D. 交-交无换向器电动机调速系统 二、判断题（每小题5分，共40分）
题目9 单相桥式全控整流电路在触发角不为零时，带反电势负载的直流侧电压比带电阻负载的直流侧电压低。

（ ）
选择一项：
对 错 题目10 IGBT器件的开通速度比晶闸管器件的开通速度快。（ ）
选择一项：
对 错 题目11 降压型DC/DC变换器的输出电压与占空比成正比。（ ）
选择一项：
对 错 题目12 异步电动机变频调速时，低速时通常需要在恒端电压/频率的基础上适当减小定子电压来补偿定子电阻压降的影响。（ ）
选择一项：
对 错 题目13 规则采样法实现SPWM时，采用载波正峰值采样的方法更准确。（ ）
选择一项：
对 错 题目14 旋转变压器只能测量速度大小，无法输出转轴的绝对位置信息。（ ）
选择一项：
对 错 题目15 无换向器电动机调速系统在高速运行时通常采用电流断续法进行换流。（ ）
选择一项：
对 错 题目16 交-交无换向器电动机调速系统在低速运行时通常采用电源换流的方法进行换流。（ ）
选择一项：
对 错 三、综合题（每小题10分，共20分）
为了加快系统响应速度，晶闸管-电动机直流调速系统通过采用转速外环-电流内环的双闭环控制方式来实现理想起动过程。

题目17 在起动过程中，如果速度调节器处于饱和限幅状态，此时系统表现为（ ）调节特性。

选择一项：
A. 恒反电势 B. 恒电流 C. 恒转速 D. 恒电压 题目18 起动过程结束后，电动机的转速与设定转速的关系为（ ）。

选择一项：
A. 电动机的转速等于设定转速 B. 电动机的转速大于设定转速 C. 电动机的转速小于设定转速 D. 二者转速关系无法确定 采用交-直-交无换向器电动机调速系统可以平滑实现四象限运行。

题目19 无换向器电动机的速度调节主要通过控制（ ）实现。

选择一项：
A. 整流侧触发角α B. 零电流检测单元 C. 转子位置检测器 D. 换流超前角γ0 题目20 无换向器电动机高速运行在第三象限电动状态时，对应的整流侧触发角和换流超前角分别是（ ）。

选择一项：
A. α>90°, γ0=180° B. α<90°, γ0=120° C. α>90°, γ0=120° D. α<90°, γ0=180°