—Whendidtheclassroomhaveapowercut?—Thismorning,whilewe

問題詳情：

—When did the classroom have a power cut?

—This morning, while we ________ a physics lesson.

A. have had            B. were having            C. are having             D. will have

【回答】

B

知識點：動詞時態

題型：選擇題