How can they learn anything they spend all their spare time watching television?
A. when
B. though
C. while
D. before
网友回答
(答案→)A. when
B. though
C. while
D. before
解析：考察连词辨析。A当…时；既然；B尽管，即使；C当…时；然而；D在…之前；句意：既然他们已经把所有的空闲时间都花在了看电视上，他们又怎么能够学到知识呢？根据句意本句中的when表示“既然”；故A正确。