题目内容
They________a chemistry experiment when suddenly their clothes caught fire.
A.did B.were doing
C.had done D.would do
B
考查时态。由语境“做化学实验时,他们的衣服突然着起火来”以及从句的时态(一般过去时)可知do是过去某时正在进行的动作,故选过去进行时。
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题目内容
They________a chemistry experiment when suddenly their clothes caught fire.
A.did B.were doing
C.had done D.would do
B
考查时态。由语境“做化学实验时,他们的衣服突然着起火来”以及从句的时态(一般过去时)可知do是过去某时正在进行的动作,故选过去进行时。