All that should be done has already been done.是什么从句,

all the things should be done have been done already all that can be done has been done Has all that can be done been done? all that can be done has been done. 在all that should be done has been done用了has,但在all that shoul all that can be done been done. I am satisfied _ should be done has been already done.A.what all that can be done has been done 为什么要用has,不用have all that can be done has been done.中的that为 Everything that can be done has been done,___? Everything can be done has been done.请问这里can be done 用的是什么时态 All that is worth ____ should be well done .