5. 两个或多个并列的that引导的宾语从句，只有第一个that可省

Mr. smith told the workers (that) John had worked very hard and that he wanted him stay.

4. it作形式宾语，that 引导的真正宾语从句

They want to make it clear to the public that they do an important and necessary job.

3. 同位语从句

Once Aristotle had made up his mind that heavy objects always fell faster than light objects.

that不充当任何成分，what可以在从句中充当成分：主语、宾语、表语。that在宾语从句中可以省略。下面几种情况不可以省略：

1．主语从句　　　 2. 表语从句

7.　 宾语从句前移Whether she will win the game, I’m not sure.

4．不定式之前　　　　 5．紧跟or not　　　 6.　 同位语从句

1．主语从句句首　　　 2．表语从句　　　　 3．介词之后

1．只要表示“命令、建议、要求”的各类名词性从句，都要用虚拟语气 should + 动词原形，should 可以省略。

2．在主语从句、表语从句或同位语从句中，也要注意主从句的谓语动词要一致，关键要注意动作发生的先后。

Who will win the first prize in the contest is not known to us.

Have you any idea why he was so rude?

1．在宾语从句中，当主句是一般现在时，其从句的谓语根据各种需要用各种时态

　　　　　 Mary is very diligent.　　　　　　　　　　 Mary was very diligent.

　　　　　 Mary is reading English.　　　　 Tom said　 Mary was reading English.

Tom says 　Mary will give us a talk.　　　　　　　　　 Mary would give us a talk.

　　　　　 Mary has been caught in the rain.　　　　 　　Mary had been caught in the rain.

　但是，宾语从句表示事实、格言、谚语等，从句的时态仍用一般现在时。