7.Although the causes of cancer ____, we
题型:选择题
问题:
7.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
7.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