名词性从句讲解
I．语序问题
规律一：名词性从句在句中要用陈述语序

II．引导词的选择
1.从句是陈述句转化而来的，不含有疑问意义。由that
引导且that连词在从句中不作成分
2.从句是由一般疑问句转化而来，含有疑问意义的。由whether，if 引导
3.从句是由特殊疑问句转化而来，含有疑问意义的。由wh-连词引导且 wh-
连词在从句中作成分。连接代词what / who/ which / whose / whatever / whoever
/ whomever / whichever，连接副词where / when / why / how / wherever /
whenever。

规律二： whether和if的区别
①whether和if在宾语从句中可以互换，但是作介词宾语时连接词一般用whether。如：
It all depends on whether they will come back.
②后面直接跟or not 时用 whether。如：
I didn’t know whether or not he had arrived in Wuhan
③主语从句和表语从句中只能用whether。如：
Whether the meeting will be put off has not been decided yet.
The question is whether they have so much money.
④whether可以引导同位语从句，用以说明前面的名词的内容，if不能。如：
We ought to discuss carefully the question whether we can do it or not.
⑤whether常与or连用表示一种选择，if不能这样用；whether也可与动词不定式连用但i
f不能。如：
The question of whether they are male or female is not important.
I have not decided whether to go or not.
⑥
whether可引导一个让步状语从句表示“不管”、“无论”，而if不能，但可以引导一个条件
状语从句表示“如果”如：
Whether he comes or not, we will begin our party on time.
If I have time tomorrow, I’ll go to visit Tom

规律三：主语从句和宾语从句在适当的情况下可以借助 “it” 而后置。
1.主语从句可以用it （作形式主语） 来替换成以下几种结构表达。
(A)It is clear/certain/likely
/true/surprising that…
（B）It is a pity/shame
/good idea/no wonder that ...
（C）It is said/reported/ believed/known/thought
/suggested that …
（D）It seems/happens that…
2.宾语从句可以用it（作形式宾语） 来替换的句型为：
主语＋谓语＋it＋Adj/N＋从句如：
I think it necessary that we have the meeting．

规律四：whatever, whichever, whoever, whenever, wherever, however 等与
no matter what, no matter which, no matter who, no matter when, no matter
where, no