Although the causes of cancer ________, we do not yet have any practical way to prevent it.
A.have uncovered | B.have been uncovering |
C.are uncovering | D.are being uncovered |
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Although the causes of cancer ________, we do not yet have any practical way to prevent it.
A.have uncovered | B.have been uncovering |
C.are uncovering | D.are being uncovered |