“How long have you worked on the farm?” “ the end of last year.”A. InB. ByC. AtD. Since

问题补充：

“How long have you worked on the farm?” “ the end of last year.”

A. In

B. By

C. At

D. Since

答案：

A. In

B. By

C. At

(答案→)D. Since

解析：用 since the end of last year 回答 how long，即问句问“工作了多久”，答句说“自去年年底至今”。