Mark was a student at this university from 1999 to 2003,___he studied very hard and was

题目

Mark was a student at this university from 1999 to 2003,___he studied very hard and was
为什么不能用during whose time . 急,请大虾们帮帮忙!
四年的时间不可以看成是whosetime 吗？

答案

答案可以是when或者during which（介词+which=关系副词）