A long time since he Shanghai.
A. have passed, left
B. has passed, left
C. have past, has left
D. has past, left
网友回答
A. have passed, left
(答案→)B. has passed, left
C. have past, has left
D. has past, left
解析：句意:自从他离开上海，已经过去很长一段时间了。结合语境可知主句描述的是现在已经完成的动作，故用现在完成时态。前文主语是抽象名词，不可数，故助动词用单数。从句中强调的是过去的动作，故用一般过去时态。Pass的过去分词时passed，选B。