Although the causes of cancer , we do not yet have any practical way to prevent it.
A. are being uncovered
B. have been uncovering
C. are uncovering
D. have uncovered
网友回答
(答案→)A. are being uncovered
B. have been uncovering
C. are uncovering
D. have uncovered
解析：考查时态。句意：尽管癌症的原因正在在揭开，我们仍然还是没有任何实用的方法来预防癌症。根据句意说明癌症的原因正在被揭开，使用的是现在进行时的被动语态。故A正确。