How can they learn anything they spend all their spare time watching television?A. whenB.

问题补充：

How can they learn anything they spend all their spare time watching television?

A. when

B. though

C. while

D. before

答案：

(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。