【题目】Sofia looked around at all the faces: she had the impression that she _____ most of the guests before.
A.has seen
B.had seen
C.saw
D.would see

【答案】B
【解析】句意：Sofia向周围看了看所有的人，她对于以前见过的大多数客人都有印象。before与完成时连用，根据动词had可知这里用的是过去式，而这里动词see发生在had之前，所以应是过去的过去，故应该用过去完成时。故选B。