—How long do you think it will be man can finally solve the problem of cancer?
—Well，it depends
A. when
B. until
C. after
D. before
网友回答
A. when
B. until
C. after
(答案→)D. before
解析：考查连词：句意：你认为还要多久人才能最终解决癌症的问题。--那要看情况而定了。这句话用了It will be+一段时间+before从句，意思是“还要多久…才/就….”，选D。