1、主语从句考点透视主语从句是名词性从句中的一种，在句子中充当主语。请仔细阅读下面课本中的主语从句，体会其引导词的用法。本期主要讲解一下主语从句引导词的使用。What is even more important is that as the earth cooled down, water began to appear on its surface. (P26)Why they suddenly disappeared still remains a mystery. (P26)So whether life will continue on the earth for millions of
2、 years to come will depend on whether this problem can be solved. (P26)引导主语从句的连接词有以下几种：一、连词that和whetherthat引导主语从句时，只起引导作用，没有具体意义，在从句中也不作任何成分，但通常不能省略。如：That the college will take in more new students this year is true.whether引导主语从句时，表示主语从句意义的不确定性，在从句中不作成分，但有意义，作“是否”解。如：Whether he can finish his task
3、on time is of great importance.一般说来，已经确定的事情由that引导，没有确定的事情由whether引导。二、连接代词what, which, who, whom, whose等连接代词在句子中既有疑问含义，又起连接作用，在从句中可作主语、宾语、表语、定语等。what引导主语从句时，相当于the thing(s) that，它本身在从句中充当主语、宾语或表语。如：What we need is more information. Who will go to the energy conference is not important. Which team w
4、ill win the match is still unknown. Whose wallet this is is not known yet. 三、复合代词whatever, whoever, whichever, whomever在从句中不含疑问意义，它们引导主语从句时，在句中用作主语、宾语、表语等。whoever = the person who或anyone who; whatever = anything that; whichever意思是“无论哪一个”。如：Whoever makes mistakes must correct them.Whichever of you co
5、mes in first will receive a prize.Whatever I have done is only for you.四、连接副词where, when, how, why, wherever以及how many / much / far / long / soon.等连接副词本身有意义，并在从句中作状语。如：How they will solve the serious problem has not been decided. Where we can look up his address is still a problem.Why he did that wa
6、sn?蒺t quite clear.How much water is flowing can be easily measured.Wherever he goes has nothing to do with me.五、it作形式主语英语中为了保持句子平衡，常用先行词it代替主语从句，而把主语从句放到后面。这时需要注意不能用that, this或these等作先行词。如：It is a pity that she has made such a mistake. It depends on the weather whether they are going shopping today.