句型转换。

1.My family went to the beach last week.(对划线部分提问)

_____ _____ _____ family _____ last week?

2. Sally often does some reading in the morning. (改为否定句)

    Sally _____ often _____ reading in the morning.

3. Ann went to the mountain by car .(对划线部分提问)    

_____ _____ Ann _____ to the mountain?

4. My vacation was great! (对划线部分提问)

_____ _____ your vacation?

5. I went to summer camp during my holiday. (改为一般疑问句并作否定回答)

—_____ you _____ to summer camp during your holiday?

—_____, I _____.

如图所示，质量为m的物体放在水平放置的钢板C上，与钢板的动摩擦因数为μ。由于受到相对于地面静止的光滑导槽A、B的控制，物体只能沿水平导槽运动。现使钢板以速度V₁向右匀速运动，同时用力F拉动物体（方向沿导槽方向）使物体以速度V₂沿导槽匀速运动，求拉力F大小。