Question

(   ) 1. How time flies!Three years ______since we came back from England. 

A. have passed B. has passed

C. are passing D. is passing

Answer 1

l.B since引导的时间状语从句其主句常用现在完成时；three years意为"三年时间"，作主语时，谓语动词一般用单数形式。