主语从句详解一、概述在句子中起名词作用的各种从句统称为名词性从句.根据它们在句中的语法作用, 这类从句又可分为主语从句、同位语从句、表语从句和宾语从句.二、主语从句主要有四类(1) 由连词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.例如:That you will win the medal seems unlikely.That you are so indifferent bothers me.That she survived the accident is a miracle.(2) 用连词 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, 只能用whether.例如:Whether we will hold a party in the open air tomorrow depends on the weather. Whether she is ing