Did you konw__at the bus stop?

题目

Did you konw__at the bus stop?
选项
A.who are they waiting for
B.whom they are waiting for
C.whom they were waiting for

答案

C.whom they were waiting for
这是一个宾从,宾从中要用陈述句语序,又主句用了Did ,因此宾从中要用过进,而不是现进.
句意:你当时知道他们在车站等谁吗?