题目内容：

1.Tom is good at drawing_____John does well in playing football.
A because B when C while D since
2.----How long do you suppose it is_____she left for America?
----No more than half a month.
A when B since C before D after

优质解答

1 c 前后两者做类比,解释为“而”
2 c ,since主句要用现在完成时的,所以错