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.

压力容器使用单位应对压力容器操作人员定期进行专业培训与安全教育，压力容器操作人员应持证上岗。