职称英语:职称英语语法辅导之名词性从句
2011-12-07 13:40:24   来源：   作者：  评论：0 点击：

④that和what的区别。
that 引导名词性从句时，在主从句中不以当任何句子成分，也没有任何含义；而what引导名词性从句时，在主从句中都要充当一定的句子成分，what可以分解成定语从句中的先行词 + 关系代词即常说的先行词 + that。如：
It’s shame that he has made such a mistake. Do what he says.
⑤同位语从句与定语从句中that的区别。
同位语从句中的连词that只起连接作用，在从句中不担当任何句子成分；而定语从句中的关系代词that在句中做宾语或主语，宾语与先行词有修饰关系。如果句子是同位语从句，就应用连词that而不能用which.同位语从句一般放在表具体含义的名词后解释名词的含义或内容，如以下名词：news、fact、suggestion、truth、plan、belief、doubt、possibility、idea等，而定语从句只是对先行词的限定和修饰。如：
They expressed the hope that they would come to visit China again.（同位语从句）
The hope she expressed is that they would come to visit China again.（定语从句）
（2）whether和if的用法。
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if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间接引语位于句首时或者是间接引语提前时用whether不用if。如：
Thank you， but whether I’ll be free I’m not sure at the moment.
⑦whether可引导一个让步状语从句表示“不管”、“无论”，而if不能。如：
Whether he comes or not， we will begin our party on time.
（3）疑问词 + ever和no matter + 疑问词的区别。
①疑问词 + ever可引导名词性从句，在主从句中要充当一定的部分。如：
Whoever breaks the rule must be punished.
You can choose whatever you like in the shop.
②疑问词 + ever还可引导让步状语从句。如：
Whoever breaks the rule， he must be punished.
Whatever you do， you must do it well.
③no matter + 疑问词只能引导让步状语从句。如：
No matter what you do， you must do it well.
No matter who breaks the rule， he must be punished.
（4）when和where引导的同位语从句与定语从句的区别。
when 和where前面的名词若是表示时间、地点的名词，则when和where引导的是定语从句，否则则为同位语从句。如：
They put forward the question where they could get the money.
This is the place where the accident happened.