When the teacher came into the classroom, the students .
A. stop to talk
B. stopped to talk
C. stopped talking
D. stop talking
网友回答
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。