问题详情：
Lin Tao has returned from the UK recently. He ______ at Cambridge for four years, during which we ______ with each other on the Internet.
A. has studied; has communicated B. had studied; communicated
C. studied; had communicated D. studied; communicated
【回答】
D
知识点：一般过去时及其被动式
题型：选择题
