Robert is said abroad, but I don’t know what country he studied in.
A. to have studied
B. to study
C. to be studying
D. to have been studying
网友回答
(答案→)A. to have studied
B. to study
C. to be studying
D. to have been studying
解析：
A。根据句中的 studied 可知，他曾到国外留过学，也就是说“留学”这个动作已结束并发生在谓语动作(is said)之前，故用完成式，即选 A。