When the teacher came into the classroom the students .A. stop to talkB. stopped to talkC

问题补充：

When the teacher came into the classroom, the students .

A. stop to talk

B. stopped to talk

C. stopped talking

D. stop talking

答案：

A. stop to talk

B. stopped to talk

(答案→)C. stopped talking

D. stop talking

解析：本题的从句为过去时，所以主句应用过去时的一种，故本题不选AD，本题的含义是当老师走进教室，学生们应该是停止说话，stop to talk指停下来说话的意思，而stop talking指停止说话，故本题选C。