Once harm is done to the environment,it takes years to have the system recovered.这是什么从句?哪是从句,哪是主句?

once harm is done to the environment,it takes years to have the system _A recoverB recoveringC recoveredD to recover Once harm is done to the environment,it takes years to have the system recovered.这是什么从句?哪是从句,哪是主句? Once harm ( )to the environment,it takes years to have the system recovered 括号里填什么,为什么A.does B.is done C.will be done D.be done Once harm is _______ to the eco-system,all species will ________,including man himself.A.made; be in danger B.done; be dangerous C.caused; be endangered D.done; be in danger 是No harm is done to your health if...还是no harm does to your health if.如题 The research is so designed that once begun nothing can be done to change 求详解once begun还是once beginning?The research is so designed that once begun,nothing can be done to change it.我知道此处是省略了once (it is )begun,但once beginning 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, Drinking polluted _water the healthA do harm to B does harm to C is harmful for B does harm to What you have done might do harm to other people.详细分析一下句子结构,哪是主谓宾What is important is to learn English这句话也是主语从句只不过句型变了，这句话里面的两个is 和What you have done might do harm to o Drinking too much your health.A.do harm to B.is harmful C.does harm to D.do harm The research is so designed that once begun nothing can be done to change it.The research is so designed that once begun nothing can be done to change it.为什么是once begun 为什么不是once begin.once negun=once itis begun那算被动语态了 no harm done怎么读 No harm done的音标 The research is so designed that once ___（begin ）nothing can be done to change it 正确形式填空 Once harm___,it takes many years to have thescar cured ,even all his life 为什么填is done?