按要求完成句子。

1.  We start school at eight o'clock.  (改为否定句)

    We _____ _____ school at eight o'clock.

2. They have lunch at school. (改为一般疑问句, 并作肯定回答)

    _____ they _____ lunch at school?

    _____,  they _____.

3. I have three lessons in the afternoon.  (改为一般疑问句,并作否定回答)

    _____ you _____ three lessons in the afternoon?

    _____, I _____.

4. I go home at five o'clock.  (对划线部分提问)

    _____ _____ _____ you go home?

开关的液压机构当分闸闭锁信号表示后有什么后果？（）

A.不能分闸，还可以合闸

B.不能分闸，也不能合闸

C.不影响开关正常运行，保护可以跳闸