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 doesnt 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 dont 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 hasnt 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.