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 be studied
网友回答
(答案→)A. to have studied
B. to study
C. to be studying
D. to be studied
解析：句意：据说罗伯特曾经在国外学习，但是我不知道他曾经在哪个国家学过。这里主要考查用动词不定时的什么形式，根据what后的从句的谓语动词studied可知，学习放生在过去，现在已经不在那里学习了，又因为is said与study abroad动作的先后来看，应是先发生study abroad，所以表示非谓语动词的动作先于谓语动词的动作，需用不定式的完成时，故选A。