问题
问答题
什么叫平面连杆机构的死点位置
答案
参考答案：在曲柄摇杆机构中，以摇杆为主动件，当曲柄与连杆处于共线位置时，通过连杆加于曲柄的力恰巧经过曲柄的转动中心，因此无论作用力有多大，也不能推动曲柄转动，使机构处于卡死现象，机构的这种位置称为死点位置。
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什么叫平面连杆机构的死点位置
参考答案：在曲柄摇杆机构中，以摇杆为主动件，当曲柄与连杆处于共线位置时，通过连杆加于曲柄的力恰巧经过曲柄的转动中心，因此无论作用力有多大，也不能推动曲柄转动，使机构处于卡死现象，机构的这种位置称为死点位置。
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| Farley worked for the Canadian government. One day, he was 1 to learn more about wolves. Do wolves kill lots of caribou(big animals)? Do they kill people? They gave him lots of food and clothes and guns. Then they put him on a plane and took him to 2 . The plane put him down and went away. There were no houses or people in this place, but there were lots of animals and lots of wolves. People tell terrible stories about wolves. They say wolves like to kill and eat people. Farley remembered these stories, and he was 3 . He had his gun with him 4 . Then one day, he saw a group of wolves. There was a mother wolf with four baby wolves. A father wolf and another young wolf lived with them. Farley watched these wolves every day. The mother was a very 5 mother. She gave milk to her babies. She gave them lessons about life. They learned how to 6 food. The father wolf got food for the mother. The young wolf 7 the children. They were a nice, happy family-a wolf family. Farley did not need his 8 any more. In a short time, he got on well with the wolf family. Farley watched them for five months. He learned many new things about wolves. He learned that many stories about the wolves were 9 . Wolves do not eat people, and they do not eat many large animals. And he also learned bad things about men. It was men who killed many caribou and wolves. Later, Farley wrote a book about wolves. He wanted people to 10 them and not to kill them. | |||
| ( )1. A. seen ( )2. A. a small town ( )3. A. afraid ( )4. A. at times ( )5. A. bad ( )6. A. cook ( )7. A. shouted at ( )8. A. food ( )9. A. not good ( )10.A. grow | B. told B. a big city B. happy B. all the time B. good B. make B. looked into B. clothes B. not true B. have | C. heard C. a far place C. angry C. once a week C. hungry C. get C. laughed at C. gun C. not easy C. teach | D. soun d D. a lonely village D. tired D. every afternoon D. thirsty D. pick D. played with D. plane D. not clear D. understand |