the end of last term we had learned 3 000 English words.A. AtB. ByC. ToD. On

问题补充：

the end of last term, we had learned 3,000 English words.

A. At

B. By

C. To

D. On

答案：

A. At

(答案→)B. By

C. To

D. On

解析：考查介词。by the end of到……时为止，固定搭配，句意：到上学期结束为止，我们已学3000个英语单词。