Question

--Did you see the traffic accident yesterday?

--Yes. It happened when I _________ past the museum.

1. A.
   walk
2. B.
   am walking
3. C.
   will walk
4. D.
   was walking

Answer 1

D
由yesterday知要用过去时，“当我正走过博物馆时，事故发生了。”因此用过去进行时。