英文语法: which能否引导同位语从句
Source: Zhihu
(prepared by: alexcwlin; edited by: Adam Lam)

Question:

which到底能不能引导同位语从句?

很多人说不能，包括有些参考书上都这么说。那么怎么解释 I have no idea which one I should buy. 这种句子? 这难道不是which引导的同位语从句吗？总不能硬说是定语从句吧，很明显这里which并不是指代idea的，而是在从句里作one的定语，语法上完全可以用what来替代which one 变成 I have no idea what I should buy. 所以，which 到底能不能引导同位语从句?

alexcwlin comments:

Your question is: Can “which” introduce an Appositive (同位语) Subordinate Clause (从句)?

The answer to that question is “Yes”.

That is, “which” can introduce an Appositive Subordinate Clause?

By definition, an Appositive is a Noun Phrase or Noun Clause which renames the Subject. (https://parentingpatch.com/appositive-english-grammar/)

An example of an Appositive Clause in a sentence at https://englishsentences.com/appositive-phrase/ is: “The dog, who loved popcorn, could often be spotted at the fair.” Both “who” and “which” are Relative Pronouns introducing clauses.

I would like to point out that the Clause “which one I should buy” in your quoted example “I have no idea which one I should buy” is not an Appositive Clause. It doesn’t “rename” the Object “idea” (which would make it an Appositive Clause). It’s an Adjectival Clause which tells more about the “idea”.

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