Question

【题目】The teacher came into the classroom while the students _________ their homework.

A. are doing B. did C. were doing

Answer 1

【答案】C

【解析】

句意：当学生们正在做作业的时候，老师走进了教室。are doing正在做，现在进行时；did做，是do的过去式；were doing正在做，过去进行时。根据句中The teacher came into…可知，这句话用的是过去时态，且从句中表示的是正在进行的动作，因此应用过去进行时态，选C。