Young people tend to get up very late unless to rise early.
A. required
B. requiring
C. they were required
D. to require
网友回答
(答案→)A. required
B. requiring
C. they were required
D. to require
解析：考查非谓语动词。当unless引导的状语从句与主句主语一样时，可以省略，用they are required，故选A。