改错

1.He said that he couldn't help but to cheat his girlfriend.

2.These old people are concerning about the growth of the younger generation.

3.To have been caught a sandstorm was a terrible experience.

4.What the teachers said will have an effect in their students.

5.Most of what has been said about the Smiths are also true of the Johnsons.

在中性点接地系统中用电设备的外壳应采用（）。

A、保护接地

B、保护接零

C、重复接地