which

An interrogative and relative determiner used to ask for information specifying one or more people or things from a definite set, or to introduce a clause providing additional information about a noun.

• 🇨🇳疑问词或关系词，用于在有限范围内进行选择、询问或进一步说明。

1. Interrogative selection A1 formal

   Used in questions to ask for information specifying one or more people or things from a known or limited set of possibilities.

   • Which book do you prefer?
   • Which way should we go?
   • Which students have finished the test?

   🇨🇳疑问选择

2. Relative reference (defining) B1 formal

   Used to introduce a relative clause that provides essential information to identify the noun it follows. Often interchangeable with 'that' in restrictive clauses.

   • The car which I bought is red.
   • This is the house which Jack built.
   • She wore the dress which she had made herself.

   🇨🇳关系指代（限定性）

3. Relative reference (non-defining) B2 formal

   Used to introduce a relative clause that adds extra, non-essential information about a noun. It is usually separated by commas and cannot be replaced by 'that'.

   • My car, which is ten years old, still runs well.
   • The conference, which was held in London, was a success.
   • He gave me a letter, which I read immediately.

   🇨🇳关系指代（非限定性）