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
Tom ought not to （） me your secret, but he really meant no harm.

A．have told
B．tell
C．be telling
D．having told
单项选择题
It is recognized by more and more people that each man and woman （） the same lights.

A．has
B．have
C．had
D．is having
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