We must do whatever we can _____ the river _____ any more.
A.to keep; polluted | B.to prevent; being polluted |
C.keep; polluted | D.prevent; being polluted |
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We must do whatever we can _____ the river _____ any more.
A.to keep; polluted | B.to prevent; being polluted |
C.keep; polluted | D.prevent; being polluted |