If we do not deal with ________ problem caused by air pollution, our planet may no longer be ________ healthy place for us.
A.a; the | B.a; a |
C.the; a | D.the; the |
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If we do not deal with ________ problem caused by air pollution, our planet may no longer be ________ healthy place for us.
A.a; the | B.a; a |
C.the; a | D.the; the |