Question

【题目】—What were you doing the fire happened?

—I was watching TV at home.

A. if B. while C. when D. since

Answer 1

【答案】C

【解析】句意：-火灾发生时你在干什么？-我在家看电视。A. if连词，如果，引导条件状语从句；B. while连词，当…时候，引导时间状语从句，谓语动词为延续性动词；C. when连词，当…时候，引导时间状语从句，谓语动词既是延续性也可是暂时性的；D. since连词，自从，引导时间状语从句。happened暂时性动词，故选：C。