英语从句的种类及用法

从句按其在主句中的句法功能可分为三类，即名词性从句、形容词性从句(即定语从句)和副词性从句(即状语从句)。引导从句的词称作关联句。
名词性从句包括主语从句、表语从句、宾语从句和同位语从句。引导这些名词性从句的关联词包括:
从属连词that, if, whether;
连接代词who, whoever, whom, whomever, which, whichever, what, whatever, whose;
连接副词where, when, why, how。
其中, 从属连词只起连接作用, 在从句中不充当任何句法成分,而连接代词和连接副词既起连接作用, 在从句中又充当一定的成分.
That Owen should have married his cousin is not at all surprising.
The fact is that he didn't go to the dinner party.
I don't know if he will attend the meeting.
Have you heard the news that Mary is going to marry Tom?
你听说玛丽要和汤姆结婚的消息了吗?(that引导同位语从句)
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1. 在含有主语从句的复合句中, 为保持句子平衡, 常用it作形式主语,而将真正的主语从句置于句末.
It's well known that water is indispensable to life.
2. 为保持句子平衡, that引导的宾语从句也常用it代替, 而将真正的宾语从句置于主句句末。这常常出现在主句有形容词或分词作宾语补足语的情况下。
He made it quite clear that he preferred to live here.
3. 从属连词whether和if都作“是否…”解, 但if不可引导主语从句和表语从句。whether可与or(not)连用, 而if不可以。
I don&#