I didn't know when they ( ) for beijingA.leftB.leaveC.are leavingD.were leaving
问题描述:
I didn't know when they ( ) for beijing
A.left
B.leave
C.are leaving
D.were leaving
答
A.
didn't后面跟过去式,排除掉BC
leave是瞬间动词,不能用were leaving
答
D
答
A.
我不知道他们什么时候动身去的北京.
过去时了.主句都是过去时.