As is reported, it is 100 years Qinghua University was founded.
A. when
B. before
C. after
D. since
网友回答
A. when
B. before
C. after
(答案→)D. since
解析：句意:正如报道的,自从清华大学成立到现在已经100年了。when 当......时候；before 在......之前； after 在......之后；since 自从。It is /has+时间段+since+sb.+did sth.自从某人做了某事已经多长时间了。故选D。