质量为 m 的小球由轻绳 a 、 b 分别系于一轻质木架上的 A 和 C 点,绳长分别为 l a 、 l b ,如图 10 所示,当轻杆绕轴 BC 以角速度 ω 匀速转动时,小球在水平面内做匀速圆周运动,绳 a 在竖直方向,绳 b 在水平方向,当小球运动到图示位置时,绳 b 被烧断的同时轻杆停止转动,则 ( ) 图 10
【简答题】根据句意,用所给词的适当形式填空。 1. They received lots of ________ (compliment) on their wonderful performance. 2. He ________ (stick) his fork into a big piece of meat. 3. Thanks for ________ (invite) me to your bi...
【简答题】根据句意用所给词的适当形式填空。 1. There ________ (be) some pictures on the wall. 2. That is ________ (Amy) photo. 3. ________ (be) her dictionary on the sofa? 4. Can you ________ (bring) these books to school? 5. W...
【简答题】词汇:根据句意及所给汉语提示,写出所给词的适当形式。 1. There are several big _____ (实验室) in their new school. 2. That book _____ (译成汉语) by that man two years ago. 3. We must _____ (专注于) our study. 4. I was told to _____ (注意发音...