典型的名词从句具有以下及格特色:
主语位置。主语从句的连接词 that 不可省略。当从句很长时可以用 it 这个虚词(expletive)来填入主语位置,名词从句则向后移。例:
That he didn't show up on time is strange.
It is strange that he didn't show up on time.
(真是奇怪,他没有准时来。)
宾语位置。宾语从句的连接词 that 在句子结构清晰的情况下(可清楚辨认出是宾语从句)可以省略。当宾语从句太长,后面又还有句子成分时,也可以借用虚词 it 暂代宾语位置,并将从句后移。例:
The defendant said (that) he didn't do it.(被告说那不是他做的。)
I find it strange that he didn't show up on time.(我觉得奇怪,他竟然没有准时来。)
补语位置。补语从句的连接词 that 省略规则同宾语从句,只要不会产生断句的困难或意思的混淆即可。例:
The car is ruined. The important thing is (that) we're all right.(车子报销了,要紧的是我们都安然无恙。)
同位语位置。同位语从句的连接词 that 不可省略,且须放在同位语位置。某些句子看似没有同位语的位置,但实际上是有的,因为这些句子省略了不重要的介系词短语,而同位语对应的词就在该短语中。例:
The story that he once killed a man might just be true.(他杀过人这件事极有可能是真的。)
I am afraid (of that thing) that I can't help you.(解析:该从句为 that thing 的同位语,翻译:对不起,我帮不了你。)
You'd better take care (of that thing) that nothing goes wrong.(解析:同上,翻译:你最好小心,别出错。)
名词从句的放大。名词从句的内容,有时比主要从句重要,这时候可以选择把名词从句当成主要从句处理,反而把主要从句缩小,放入括弧性的逗号当中。放大处理的过程是,把连接词省略掉,再移到前面,使它看起来像主要从句,再把主要从句后移到逗号后。例:
原句:I suppose that this is your last offer.
放大:This is your last offer, I suppose?
(我想这就是你们的最后报价吧?)
名词从句中有引用句的,不仅可以放大,还可以倒装。因为句子放大后,可能会使主语与动词之间的距离太远,所以可以使用倒装来解决这个问题。例:
原句:Dr. Chang, Director of the Yangmingshan Geological Observatory, said that the earthquake was a 6.9.
放大:The earthquake was a 6.9, Dr. Chang, Director of the Yangmingshan Geological Observatory, said.
倒装:The earthquake was a 6.9, said Dr. Chang, Director of the Yangmingshan Geological Observatory.
(这场地震为6.9级,阳明山地质观测站主任张博士如是说。)
疑问句改装的名词从句。以疑问词(who、what、when等)引导的疑问句,也可以改装成名词从句,代表一个问题(the question)。改装过程为,将疑问句改写为非疑问句的顺序,并直接替换主句中的 the question 位置即可 。例:
主句:I know the question.
疑问句:Who are you?
改装:I know who you are.(我知道你是谁。)
主句:The question is anybody's guess.
疑问句:When will the bomb go off?
改装:When the bomb will go off is anybody's guess.(炸弹什么时候会爆炸没有人知道。)
whether 和 if。whether 不能独立当做疑问词来引导一个带问号的疑问句,但它可以引导代表一个问题的名词从句。whether 引导的从句,可以看做是以 either 开头的子句与带 which 的主句合成的。大多数情况下可以和解释为“是否”的 if 互换使用,但是在句首位置以及介系词后面就只能用 whether 了。前者的原因是,放在句首位置的 if 从句,容易让读者误以为是表示“如果”的副词从句;后者的原因是,介系词后面必须使用名词短语,不适合使用连接词引导名词从句,但 whether 从句可以放在介系词后面,因为他是 which 和 either 合成的字,其中的 which 是代名词类,可以作介系词的宾语。例:
主句:I can't tell which.
从句:Either he's telling the truth or he's not.
合成:I can't tell whether he's telling the truth or not.(我不知道他有没有说真话。)
可用 if 替换:I can't tell if he's telling the truth or not.
主句:(The question) which is impossible to say now.
从句:Either the stock market will improve or it will not.
合成:Whether the stock market will improve or not is impossible to say now.(股市是否会涨,现在还很难说。)
此处 whether 在句首,不可用 if 替换。
主句:The treatment will be decided by (the question) which.
从句:Either the tumor is malignant or it is not.
合成:The treatment will be decided by whether the tumor is malignant or not.(治疗方法将视肿瘤是否为恶性而定。)
此处 whether 在介系词后面,不可用 if 替换。