主语从句一、主语从句的连词分三类（1）从属连词引导的主语从句 （that whether if）that引导的主语从句:引导词that无含义/在句中不做成分/不可以省。That 引导主语从句通常用it 作形式主语。例如：That you will win the medal seems unlikely. That she survived the accident is a miracle.whether 引导的主语从句: whether有含义(是否)/在句中不做成分/不可以省。注意：引导主语从句，不能用if不能在开头，只能用whether。Whether we will hold a party in the open air tomorrow depends on the weather. Whether she is coming or not doesnt matter too much.（2） 用连接代词引导的主语从句 在由连接代词who, whose, whom, which, what, whoe
