All that can be done _______(be)done

题目

All that can be done _______(be)done
All that can be done _______(be)done .We can not do anything more but have to wait and see
求详尽的解释

答案

此处应填写has been.全句意为：所有能做的我们都做了.我们不能再做任何事情,只有等待和观望.解析：主谓一致应遵循三个原则,即语法一致、意义一致、就近一致.根据语法一致,整个上下文句子都是现在时,所以此处应为现在...