— How long have you been here？— the end of last month A. InB. ByC. AtD. 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：since引导的介词短语和现在完成时连用