问题
选择题
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
答案:A
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