0 导言

名词性从句，是指一个句子相当于名词来使用，放到另外一个句子中。通常情况下，名词在句子中主要作四种成分：宾语、表语、主语、同位语。因此，名词性从句就分成四种：宾语从句、表语从句、主语从句、同位语从句。四种名词性从句写法基本相同，只是位置不同。通常出现最多的是宾语从句，其次是主语从句和同位语从句，表语从句最少

名词性从句={宾语从句表语从句主语从句同位语从句名词性从句 = \begin{cases} \text{\quad宾语从句} \\ \text{\quad表语从句} \\ \text{\quad主语从句} \\ \text{\quad同位语从句} \\ \end{cases} 名词性从句=⎩⎪⎪⎪⎨⎪⎪⎪⎧​宾语从句表语从句主语从句同位语从句​

1. 宾语从句

（一）宾语从句的含义

一个句子作宾语，放在另一个句子（主句）中 Justice Anthony Kennedy wrotethat the previous decisions were flawed.

（二）宾语从句的写法

1. 陈述句变宾语从句

变化前：Dr. Worm acknowledges(These figures are conservative).变化后：Dr. Worm acknowledgesthat these figures are conservative.

结论：陈述句变宾语从句，前加 that（that 不作成分，可以省略）。

【补充】宾语从句里的 that 可以省略，但是建议写的时候不要省。一是把 that加上更有利于分清主句和从句；二是名词性从句写法基本相同，但只有宾语从句中的 that 可以省略，而其他三种（主语从句、表语从句、同位语从句）都不能省略 that,与其浪费时间去分辨能不能省略，不如都加上更保险。但在分析句子时要

We believeconsumers should have more control.

2. 特殊疑问句变宾语从句

变化前：We suddenly can’t remember(Where did we put the keys just a moment ago?)变化后：We suddenly can’t rememberwhere we put the keys just a moment ago.

结论：特殊疑问句变宾语从句，要调整语序（疑问语序变回陈述语序，即把疑问句的主语提前到谓语动词之前，其他不变）

3. 一般疑问句变宾语从句

变化前：I don’t know(Are other clients going to abandon me, too?变化后：I don’t knowif other clients are going to abandon me, too.

结论：一般疑问句变宾语从句，先调整语序（主语提前），再前加 “是否（whether 或 if）”。但 if 有时不能使用（例如主语从句中），而 whether 在各种情况下都可以用，所以建议使用最保险的 whether。

4. 补充说明

上面的例子都是主句为陈述句，因此从句要调整成陈述语序再放入到主句中。若主句为疑问句，内部包含的宾语从句依然遵循此原则——变为陈述语序，如下：

Why do so many Americans distrustwhat they read in their newspapers?

5. 总结

观察刚才变化后的三个宾语从句，看看有什么相同点：

Dr. Worm acknowledgesthat these figures are conservative.We suddenly can’t rememberwhere we put the keys just a moment ago.I don’t knowif other clients are going to abandon me, too.

以上三个句子虽然变化之前类型不同（陈述句、特殊疑问句、一般疑问句），但是变成宾语从句后结构是一样的，都是“连接词 + 陈述句（陈述语序的句子）”。

结论：宾语从句 = 连接词 + 陈述句

（二）宾语从句的位置

宾语从句的位置一共有三种，分别是及物动词后（动宾）、介词后（介宾）、形容词后【补充】除了作为谓语的及物动词后可接宾语从句之外，非谓语动词后也可以接宾语从句，但是注意一定要是及物动词的非谓语后才可以接宾语从句。 You might even be temptedto assumethat humanity has little future to look forward to.she wantedto knowif vaccines come from animal research.they survey and sample… large areas of terrainto determinewhere excavation will yield useful information.Neither of these patterns is borne out by the analysis,suggestingthat the structures of the languages are lineage-specific and not governed by universals.【补充】如果宾语从句过长，且在主谓宾补的句型中，则宾语从句后置，用形式宾语 it 来替代： That kind of activity makesitless likelythat the court’s decisions will be accepted as impartial judgments.He says medical licensing boards “must makeitclear…that painful deaths are presumptively ones that are incompetently managed and should result in license suspension.”

2. 表语从句

（一）表语从句的含义

This kind of thinking iswhy so many people try to avoid arguments…

（二）表语从句的写法

表语从句的写法同宾语从句。但连接词为 that 时，不作成分也不能省略 Part of the issue isthat airports have only so much room for screening lanes.This iswhere developing new habits comes in.This iswhy repeated attempts at reform legislation have failed in recent years…

（三）表语从句的位置

表语从句位于系动词后,通常位于系动词 be 后，极少数情况下会出现在其他系动词后，如下：

For Williams, those activitiesbecomewhat he calls “electronic heroin.”Yet the factremainsthat the merger movement must be watched.

【补充】除了作为谓语使用的系动词后可接表语从句之外，作为非谓语动词的系动词后也可以接表语从句。简单了解即可

Human naturebeingwhat it is, most people stick with default settings.The explanation for insensitivity to smell seemsto bethat the brain finds it inefficient to keep all smell receptors working all the time but can create new receptors if necessary.

3. 主语从句

（一）主语从句的含义

一个句子作主语，放到另一个句子(主句)中What is being called artificial general intelligence…continues to evade scientists.

（二）主语从句的写法

主语从句的写法同宾语从句，但是 that 不作成分也不能省略，而且表示“是否” 时，只能用 whether,不能用 ifThat the seas are being overfishedhas been known for years.What motivated him…was his zeal for fundamental fairness”…Andwhether the community’s work contributes much to an overall accumulation of knowledgeis doubtful.

（三）主语从句的位置

主语从句的位置有两种：位于句首或句尾。同一个主语从句位于两种位置时，意思相同

1. 位于句首

Just how people thinkis still far too complex to be understood…What is neededis a technology of behavior…

2. 位于句尾

为了避免因主语从句过长而造成整个句子头重脚轻，所以通常主语从句后置，句首用形式主语 it 来代替。各种等级考试或外文中出现得最多的是主语从句位于句尾，因此要重点掌握。

Itdid not matterwhat was done in the experiment…Itis becoming less clear, however,that such a theory would be a simplification…Itmakes no differencehow you write…

【补充】主语从句在考研真题中有两种特别重要且常用的句型模板，如下：

模板 1：It is done +主语从句(表达人们对一件事的观点或看法)

This year,itwas proposedthat the system be changed…Itwas argued at the end of the 19th centurythat humans do not cry because they are sad…

模板 2：It is + adj./n. +主语从句(表达对一件事的评价)

Itis not yet clearhow much more effective airline security has become……itis obvious that their views were less fully intellectualized.Second,itis surely a good thingthat the money and attention come to science rather than go elsewhere.

4. 同位语从句

（一）同位语从句的含义

一个句子作同位语，放到另一个句子（主句）中。同位语从句的作用是解释说明一个抽象名词。 So does the ideathat decisions made by AI systems should be explainable, transparent, and fair

（二）同位语从句的写法

同位语从句的写法同宾语从句。但最常用的一种同位语从句是由 that 引导的(that + 完整的陈述句)，虽然 that 在同位语从句中不作成分，但是不能省略Evidencethat the LoveLife program produces lasting changes is limited and mixed.There is noreasonwhy everyone cannot be welcomed on Mauna Kea to embrace their cultural heritage and to study the stars.For my part, I have noideawhether Gilbert is a great conductor or even a good one.

（三）同位语从句的位置

同位语从句是用来解释名词的，所以放在名词后。但是并非所有的名词都需要解释，比如说 apple, book 等，这些不抽象的名词就不需要解释，因为大家都已经知道它们是什么了。需要解释说明的名词只有抽象名词，因此同位语从句要位于抽象名词后，考研真题中最常出现在同位语从句前的抽象名词有：idea, opinion,view, fact, evidence, question, doubt, reason, demand, theory, belief, possibility,chance, hope, contention, guarantee 等。

In other words, they all share aviewthat the international tax system has failed to keep up with the current economy.A century ago, Freud formulated his revolutionarytheorythat dreams were the disguised shadows of our unconscious desires and fears…

5. 总结