单句改错

1. It is only when he comes back can you leave.

2.  A child as he is,he knows a lot about computer games.

3. In he came when the bell rang.

4. So fast he ran that I couldn't follow him.

5. It was not until he told me did I know the news.

钢筋弯箍机开机前不用做的是（）

A.仔细检查设备是否正常

B.检查连接螺栓是否紧固可靠

C.检查气管有无泄漏

D.检查油位是否足够