主语从句 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.主语从句主要有三类： （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. 你想获得奖牌看起来是不可能的。 That you are so indifferent bothers me. 你如此冷淡使我很烦恼。 That she survived the accident is a miracle. 她在事故中幸免于难简直是奇迹。 （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。 例如：Whether she is coming or not doesn’t matter too much. 她来不来都无关紧要。 （3） 用连接代词引导的主语从句(在由连接代词 who, whose, whom, which, what, whoever, whomever, whichever, whatever 引导的名词性从句中，其连接代词在句中起名词性作用，担当一定成分). 例如：What you need is more practice. 你所需要的是更多的训练。 What I want to know is this. 我想知道的就是这事。 Whatever we do is to serve the people. 我们无论做什么都是为人民服务。 （4）用连接副词 when, where, why, how 引导的名词性从句(其连接副词有含义,在句中作状语。) eg:Where we should leave it is a problem. When they will come hasn’t been made pubic. 他们什么时候来还不知道。 三.注意点: 1.it 做形式主语,而将主语从句放在句末（尤其是当谓语较短时）。 例如：That light travels in straight lines is known to all. 光沿直线传播，这是众所周知的事。 =It is known to all that light travels in straight lines. 众所周知光沿直线传播。 When the plane is to take off has not been announced . 飞机何时起飞还没有宣布。 = It has not been announced when the plane is to take off. 还没有宣布飞机何时起飞。 (当 what 引导的主语从句表示“…的东西”时，一般不用 it 作形式主语。) 错:It is a book what he wants. 对:What he wants is a book. 他想要的是本书。 例如：Has it been settled who will be sent to carry...
