Choose the correct relative pronoun to complete the sentence: 'The laboratory ______ we conducted the experiment is now closed.'
答案解析
**Core Concept**: Grammar (relative clauses).
**Analysis**: The antecedent 'laboratory' refers to a place, requiring the relative adverb 'where' (B). 'Which' (A) would need a preposition (in which). 'When' (C) refers to time; 'whom' (D) refers to people.
**Error Check**: A lacks a preposition; C/D mismatch context.
正确答案：B