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

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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
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

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
答案A 考查被动语态.选项A是现在进行时的被动;选项B是现在完成进行时的主动语态;选项C是现在进行时的主动语态;选项D是现在完成时的主动语态.根据题意:虽然癌症的成因长在被揭示,但我们眼下还没有防止它的实用方法.故答案为A.查看原帖>>