since we have done our homework now对吗

since we have done our homework now对吗 we have done our since前用have done 还是have been done and what have we done What Have We Done 歌词 if we had been given more time ,we could have done it better it is ten years since his father died What have you done since you returned to China? we have done much为什么用much have .since did区别have .since have done?eg：I haven’t seen you since I’ve been back.I haven’t seen you since I was back. we don't have done our homework 与 we have not done our homework的区别 We all have done与we have all done哪个对 What have we done today to make we fell proud 用汉语翻译“We cannot undo what we have done” 英语翻译整句是：since we‘re done transporting you,we'll be returning home. We have been good friends since we met at school. We have called them that since we were We have done thing we ought not to have done and___undone things we ought to have done.A.left B.leave C.will leave D.leaving We have done thing we ought not to have done and___undone things we ought to have done.A.left B.leaving.为什么是A,B为什么不可以