something must to done to make our city a better place to live 中的为什么用to done,

something must do,something must not do must 加to We must do something to help her被动语态 We must do something to change their _(生活). Hope to do something we must do something to improve our english改为被动语态 We must do something to protect our environment.We should use these bags（ ） plastic bags. We must do something ________the river.A.stop polluting B.to stop polluting John has finished his homework .we must do something to protect the environment.被动语态 Something must _____(do) to prevent flood from ______.(happen)怎么填空? There is so much p() in this city.People must do something to stop it The government must do something to stop the prices of the buildings____(上升）so high. at present there must be nothing we can do to prevent the juvenile crimes怎么不用something that we can do和something which we can do We must do something.This is something.Therefore,we must do this.这话该如何解释 You must do something to help your friend.(改成否定句）You ____ _____ _____ to help your friend. there must be something wrong to it you must be something to talk we must do something to improve our english改为被动语we must do something to improve our english改为被动语态____ _____ ____ ______ to improve our english we must do something to stop the population.与另一个句子如何同意句转换something __ __ __ to stop the population.