It has been two years we left school.A. sinceB. whenC. beforeD. as

问题补充：

It has been two years we left school.

A. since

B. when

C. before

D. as

答案：

(答案→)A. since

B. when

C. before

D. as

解析：这题考查连词的用法：句型是：It is/has been +一段时间+since“自从…有多久了”，句意是：自从我们毕业有两年了。选A。