We when the teacher came in.A. were talkingB. talkedC. talkD. are talking

问题补充：

We when the teacher came in.

A. were talking

B. talked

C. talk

D. are talking

答案：

(答案→)A. were talking

B. talked

C. talk

D. are talking

解析：A “正在做某事时，某事突然发生”常用when，即be doing sth. When sth. else did（用动词的过去式）。“我们正在谈话时，老师进来了。”故用过去进行时。故选A。