单项选择题

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

A．had done
B．is done
C．is to do
D．does
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单项选择题
We should be able to do the job for you quickly,______you give us all the necessary informarion.
A．as if
B．provided that
C．in case
D．so that
单项选择题
The law requires that everyone______his car checked at least once a year.A) has B) hadC) have D ) must have
The law requires that everyone______his car checked at least once a year.A) has B) hadC) have D ) must have
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