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,
问题描述：
Once environmental damage __,it takes many years for the system to recover
A has done B is to do C does D is done 小女子有理了,
答
D
一旦环境被破坏,生态系统要花好多年去恢复.
答
选D啊, 楼上翻译非常好！
答
was done
从句是一般现在时,主句应用过去时
完成时是要用的
答
楼上很对
答
D is done
如果环境贝破坏,就会化肥很多年回复这个环境系统