问题补充:
The twins has studied in this school .
A. two years ago
B. since two years ago
C. for two years ago
D. since two years
答案:
A. two years ago
(答案→)B. since two years ago
C. for two years ago
D. since two years
解析:与现在完成时,连用的时间状语为since +一段时间+ago,for +一段时间,故选B