名词性从句是英语语法中非常常见的一种句型，它可以作为主语、宾语、表语或同位语。在构建名词性从句时，常常需要使用到一些引导词，下面就是一些常用的引导词以及它们的用法：
1. 连接代词
连接代词包括：what、which、who、whom、whose。
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What：引导主语从句、宾语从句、表语从句或者同位语从句，代表“什么”或“那个”的意思。例如：
- What I need is a good rest.
- I don't know what he wants.
- The question is what we should do next.
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Which：引导主语从句、宾语从句或者同位语从句，代表“哪一个”的意思。例如：
- Which do you prefer, tea or coffee?
- I can't decide which one to choose.
- The problem is which way to go.
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Who/Whom：引导主语从句或者宾语从句，代表“谁”的意思。例如：
- Who is coming to the party tonight?
- Whom did you meet at the conference?
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Whose：引导同位语从句，代表“谁的”的意思。例如：
- I met a boy whose mother is a famous actress.
2. 连接副词
连接副词包括：when、where、why、how。
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When：引导时间状语从句，代表“何时”的意思。例如：
- I will call you when I arrive in New York.
- I remember the day when we first met.
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Where：引导地点状语从句，代表“哪里”的意思。例如：
- Do you know where the nearest post office is?
- I can't remember where I put my keys.
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Why：引导原因状语从句，代表“为什么”的意思。例如：
- I don't understand why he left so suddenly.
- That's why I didn't go to the party.
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How：引导方式状语从句，代表“怎样”的意思。例如：
- She told me how to make a delicious cake.
- I don't know how to solve this math problem.
以上是名词性从句常用的引导词及其用法，希望对大家的英语学习有所帮助！
