冲压机的传动常用曲柄滑块机构将旋转运动变为直线运动，曲柄滑块机构运行到α=90°位置 发布时间：2017-12-14 10:18 │ 来源：www.tikuol.com 题型：单项选择题 问题： 冲压机的传动常用曲柄滑块机构将旋转运动变为直线运动，曲柄滑块机构运行到α=90°位置时，其速度为( )加速度为( )A．最大；最小B．最大；为零C．最小；最大D．最小；为零
题型：单项选择题 完型填空。 When you look into the sky at night, you can see a large number of stars. Besides, you can see the 1 too. It's bright 2 beautiful. People write many songs and poems (诗歌) 3 it. In the 1960s, some 4 wanted to be the first one to send a man to the moon. America and Russia were in this "space race". They 5 a lot of money 6 it.The 7 man in space was Yuri Gagarin, a Russian. He went into the space 8 1961.A few years later, an American spaceship flew to the moon. Neil Armstrong walked out. He was the first man 9 on the moon. China is interested in the space too. In 2003, Yang Liwei, China's hero, flew 10 the earth in space. ( )1. A. moon ( )2. A. but ( )3. A. on ( )4. A. country ( )5. A. spend ( )6. A. on ( )7. A. first ( )8. A. on ( )9. A. walk ( )10. A. around B. sun B. and B. about B. city B. spent B. in B. second B. at B. walking B. to C. earth C. or C. of C. cities C. cost C. to C. third C. in C. to walk C. towards D. stars D. / D. from D. countries D. took D. about D. fourth D. of D. walks D. through 查看答案