Question

【题目】They were smoking the teacher appeared in front of them.
A.where
B.while
C.what
D.when

Answer 1

【答案】D
【解析】句意：他们正在抽烟这是老师出现在他们面前。when这是，那是，相当于and then。while正当……的时候，其后通常跟进行时态；where哪里；what什么均不含题意。故选D。