Once environmental damage ____,it takes many years for the system to recover.A.has doneB.is done选什么?为什么?

environmental environmental environmental Once environmental damage __,it takes many years for the system to recoverA has done B is to do C does D is done Once environmental damage _______,it takes many years for the system to reca、has done b、is to doc、 does d、is done Once environmental damage __,it takes many years for the system to recoverA has done B is to do C does D is done 小女子有理了, once environmental damage ________,it will take many years for the system to recoverA has done B is to do C does D is done 错在哪?还有D表示什么回答者：匿名 12-2 00:52 xieixe environmental aerosol environmental是什么意思 We can have more ____ buildings and houses .A.environmental friend B.environmental friendlyC.environmentally friend D.environmentally friendly为什么选D不选A,请详解, Once environmental damage ____,it takes many years for the system to recover.A.has doneB.is done选什么?为什么? once! once once Once once Once once