赞题库-背景图

单项选择题

Once environmental damage ______, it takes many years for the system to recover.

A．is done
B．will be done
C．has done
D．is to be done

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热门试题

单项选择题______ will come and lend us a helping hand on such an awkward occasion

A．Do you suppose who
B．Whom do you suppose
C．Who do you think
D．Whom do you think