Many pupils can't make full use of their time, ________ they realize how valuable it is．

A.as if

B.now that

C.even though

D.so that

答案及解析： C

even though尽管；as if好像；now that既然；so that以便，为了。句意：许多学生不能充分利用他们的时间，尽管他们意识到时间是多么的宝贵。