--- How long have you been here? --- the end of last month. A. InB. By C. At D. Since

问题补充：

--- How long have you been here?

--- the end of last month.

A. In

B. By

C. At

D. Since

答案：

A. In

B. By

C. At

(答案→)D. Since

解析：此题容易选A或B。以为是考查固定短语。答案为D。表示“自从上个月末以来”。