A.is to do
B.does
C.has done
D.is done
[单选题]Once environmental damage ______, it takes many years for the system to rec
[单选题]Once environmental damage ______, it takes many years for the system to rec
[单选题]Once environmental damage( ),it takes many years for the system to recover.
[单选题]Once environmental damage( ),it takes many years for the system to recover.
[单选题]Once environmental damage( ),it takes many years for the system to recover.
[单选题]Once environmental damage( ),it takes many years for the system to recover.
[单选题]Once environmental damage_____, it takes many years for the system to recov
[单选题]Once environmental damage ___________, it takes many yearsfor the system to
[单选题]Once environmental damage(),it takes many years for the system to recover.环
[单选题]Once environmental damage __________,选择Onceenvironmentaldamage__________,ittakesmanyyearsforthesystemtorecover.A.)hasdoneB)istodoC)doesD)isdone