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。