第一关：引导词关

　　1.由that 引导的宾语从句。that 只有语法作用，没有实在的意义，在从句中不充当成分，在口语和非正式文体中可以省略。

　　例：He said (that) he wanted to stay at home.

　　She doesn’t know (that) she is seriously ill.

　　I am sure (that) he will succeed.

　　2. 由连接代词who, whom, whose, what, which 和连接副词when, where, why, how 引导的宾语从句。这些连接代词和连接副词本身有意义，在宾语从句中充当某个成分(连接代词充当主语,定语或宾语；连接副词充当状语)。

　　例：Do you know who (whom) they are waiting for?    (做宾语)

　　       He asked whose handwriting was the best.          (做定语)

　　Can you tell me where the No.3 bus stop is?        (做状语)

　　I don’t know why the train is late.                          (做状语)

　　3. 由if 或whether 引导的宾语从句。If 和whether 在句中的意思是“是否”；在从句中不充当成分。

　　例：I want to know if (whether) he lives there.

　　He asked me whether (if) I could help him.

　　注意： 一般情况下,if 和whether可以互换,但以下3种情况只能用whether:

　　①在不定式前:Whether to go there or not hasn’t been decided.

　　②在介词前:It depends on(依靠) whether it is going to rain.

　　③与or not连用:They are talking about whether to go there or not.