I first met Mr. Smith in America. He at Stanford University then.A. studiedB. has studied

发布时间：2020-08-15 00:30:05

I first met Mr. Smith in America. He      at Stanford University then.
A. studied
B. has studied
C. is studying
D. was studying

网友回答

A. studied
B. has studied
C. is studying
(答案→)D. was studying
解析：由关键词：then推出过去进行时。
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