was to do&was to have done

was to do&was to have done somebody was thought to do/ have done.句型中,何时用to do,何时have do 表愿望未达成是was to do还是was to have done be supposed to do与was/were supposed to have done what was to be done?和 what should they do? was/were supposed to do 和is/are supposed to have done是一样的意思吗 were/was to have done 可以代替would/should have done have to ,时态,Must,it is/was neccesary to do seem to do seem to have done to do 和 to have done what was to be done?怎么翻译 歌曲中含有TO DO ：TO BE DONE ：TO HAVE BEEN DONE ：TO HAVE DONE