从地球看太空的问题是空气中有很多灰尘。

　　(4)引导表语从句只能用whether，不能用if.

　　The question is if the enemy is marching towards us.(×)

　　The question is whether the enemy is marching towards us.(√)

　　(5)表语从句一定要用陈述语序

　　The question is when can he arrive at the hotel.(×)

　　The question is when he can arrive at the hotel.(√)

　　(6)不同于宾语从句，在有表语从句的复合句中，主句时态和从句时态可以不一致。

　　The question is who will travel with me to Beijing tomorrow.(√)

　　The question is why he cried yesterday.(√)

　　即时跟踪1　用适当的连接词填空

　　1．But the biggest surprise of the evening was when I was elected prom queen!

　　2．The fact is that we are short of money for the project.

　　3．He has a heart disease.That is because he has been smoking too much.

　　4．The problem with the plan is whether it will be accepted by them.

　　5．He was late and that was why he was scolded by the teacher.

　　主语从句

　　1．定义：在复合句中作主语的从句叫主语从句。

由从属连词that，whether引导 That they will win the match is certain.

他们将赢得比赛是确定无疑的。

Whether we go together or separately doesn't matter much.

我们是一起走还是分开走都没关系。

注意：引导位于句首的主语从句只能用whether，不能用if。