名词性从句详解
名词性从句（Noun Clauses）是在句子中充当名词功能的从句。它在句中可以做主语、宾语、表语和同位语。掌握名词性从句是高中英语语法的核心内容之一。
一、名词性从句的分类
根据在句中所充当的成分，名词性从句分为四类：
| 类型 | 功能 | 示例 |
|---|---|---|
| 主语从句 (Subject Clause) | 充当句子的主语 | What he said is true. |
| 宾语从句 (Object Clause) | 充当动词或介词的宾语 | I believe that he is honest. |
| 表语从句 (Predicative Clause) | 位于系动词之后充当表语 | The problem is who can solve it. |
| 同位语从句 (Appositive Clause) | 对抽象名词进行补充说明 | The news that he won excited us. |
二、引导词的使用规则
名词性从句的引导词分为三大类：
1. that（无词义，只起连接作用）
- 主语从句：That she passed the exam is surprising.（她通过了考试，这令人惊讶）
- 宾语从句：I know that he will come.（我知道他会来）
- 表语从句：The reason is that he was ill.（原因是他病了）
- 同位语从句：The fact that he succeeded proves his ability.（他成功了这个事实证明了他的能力）
注意：that在主语从句、表语从句、同位语从句中不能省略；在动词后的宾语从句中可省略。
2. whether / if（"是否"，有词义）
- whether可用于所有名词性从句
- if只能用于动词后的宾语从句，不能用于：
- 主语从句：
If he comes→ Whether he comes doesn't matter. - 介词后：It depends on whether ...（不能用if）
- 表语从句：The question is whether ...
- 同位语从句：
- 主语从句：
3. wh-疑问词（who, whom, whose, what, which, when, where, why, how）
这些词保留各自的疑问含义：
- who：谁——Who will be the leader is unknown.
- what：什么/所……的——I don't know what he wants.
- which：哪一个——Tell me which book you prefer.
- when/where/why/how：时间/地点/原因/方式——I wonder when he left.
4. whoever, whatever, whichever 等复合关系词
- whoever = anyone who（无论谁）——Whoever breaks the law will be punished.
- whatever = anything that（无论什么）——You can eat whatever you like.
- whichever = any one that（无论哪个）——Choose whichever suits you.
三、重点与难点辨析
易混点1：that vs what
| that | what | |
|---|---|---|
| 词义 | 无意义（只起连接作用） | "所……的人/事/物" |
| 语法功能 | 在从句中不作成分 | 在从句中要作主语、宾语或表语 |
| 示例 | I think that he is right. （that不作成分） | I know what he said. （what作said的宾语） |
易混点2：同位语从句 vs 定语从句
| 同位语从句 | 定语从句 | |
|---|---|---|
| 功能 | 解释说明名词的具体内容 | 修饰限定名词 |
| 引导词 | that 不作成分，不能省略 | that 作成分，可省略（作宾语时） |
| 先行词 | 抽象名词：fact, news, idea, truth 等 | 任何名词均可 |
| 示例 | The news that he was admitted to university is true. （"被大学录取"就是消息的内容） | The news that you told me yesterday is true. （"你昨天告诉我的"修饰"消息"） |
易混点3：it作形式主语/形式宾语
当主语从句较长时，常用 it 作形式主语：
- It is obvious that he is lying.（很明显他在撒谎）
- It is a pity that you didn't come.（你没来真遗憾）
- It is said that he has gone abroad.（据说他出国了）
当宾语从句后跟补足语时，用 it 作形式宾语：
- I make it clear that I disagree.（我说清楚了我不同意）
- We think it necessary that everyone should attend.（我们认为每个人都有必要参加）
四、综合练习
Exercise 1：选择正确的引导词
- ______ he needs is more experience. (What / That)
- It is still unknown ______ the meeting will be held. (whether / if)
- The question is ______ we can finish it on time. (whether / if)
- I have no idea ______ he left without saying goodbye. (why / that)
Exercise 2：判断从句类型
- The fact that the earth is round is known to all. （______ 从句）
- The fact that we discovered surprised everyone. （______ 从句）
- What surprised me most was that he didn't know the answer. （______ 从句 + ______ 从句）
📝 趣味练习：语法侦探
任务：找出下列句子中的所有名词性从句，并标明类型
What I want to tell you is that English grammar is not as difficult as you think. The truth is that many students make progress quickly once they understand the rules. I believe that you can master noun clauses if you practice enough. The question is whether you are willing to put in the effort.
参考答案
"What I want to tell you"——主语从句
"that English grammar is not as difficult as you think"——表语从句
"that many students make progress quickly"——表语从句
"that you can master noun clauses"——宾语从句
"whether you are willing to put in the effort"——表语从句
五、课后作业
Level 1：基础练习
- 用适当的引导词填空：
- ______ he passed the driving test made his parents happy.
- I don't know ______ she will come or not.
- The problem is ______ we don't have enough money.
- ______ leaves the room last should turn off the lights.
Level 2：句型转换
- People say that he is a genius. → ______ is said that he is a genius.（改为it作形式主语的句子）
- Will he come? I don't know. → I don't know ______ ______ ______.（改为宾语从句）
Level 3：写作应用
用名词性从句改写下段（至少使用3个名词性从句，并用下划线标出）：
"I think something. Time management is very important for high school students. The reason is that we have many subjects to study. Some students don't manage their time well. This is a problem."
改写示例：What I think is that time management is very important...