1.I think that I've hurt ma back.2.I'm afraid that I can't get up.

问题描述:

1.I think that I've hurt ma back.2.I'm afraid that I can't get up.
1.I think that I've hurt ma back.
2.I'm afraid that I can't get up.
3.I think that the doctor had better see you.
请问这几句话中的that是起什么作用的.可以去掉吗?

都是引导从句的
都可以省略