that引导的宾语从句,一般可以省略that,但在以下6中情况中that不可以省略:
1.在由and和but连接的两个并列的宾语从句中,第一个从句中的that可以省略,第二个从句中的that不能省略.如:I know (that) you are very kind and that you can help me.
2.当that宾语从句中的状语位于从句的前部时,that不可以省略.如:Tell him that if he comes tomorrow,please call me.
3.当that前面有插入语时,that不可以省略.如:He didn't know,I'm sure,that his mother was ill.
4.当it作为形式宾语放在动词之后,而that引导的真正宾语从句放在句尾时,that不可以省略.如:They took it for granted that the singer was coming.
5.在省略答语中,当that宾语从句单独出现时,that不可以省略.如:
----What did you say?
----That he would be here at 8 o'clock.
6.当that宾语从句是双宾语中的直接宾语时,that一般不省略.如:I swear.I will never tell anyone that you have broken the glass.