按要求完成下列各句。

1. They think the computer is very useful. (改为反意疑问句)

    They think the computer is very useful, _______ _______?

2. It is impossible that a child can lift such a heavy box. (改为同义句)

    It is impossible_______ _______ _______ _______ _______ such a heavy box.

3. You shouldn't make noise while eating noodles. (改为同义句)

    You _______ _______ _______ make noise while eating noodles.

4. Henry never goes swimming in the river. (对画线部分提问)

    _______ _______ does Henry go swimming in the river?

5. Work hard, or you will not pass the exam. (改为同义句)

    _______ you don't work hard, you won't _______ the exam.

（）混凝土外加剂看起来与食盐相似，是有毒物品，要严防误食。

A、氯化钠

B、亚硝酸钠

C、尿素

D、树脂