改错题一题

两个地方错了，all 后面的宾语从句缺主语，that不能少，还有就是been。所以因该是Has all that could be done been done to save the injured?

Has all could be done “be” done to save the injured?
“be”有问题，改为been
分清主谓宾："All could be done" has been done to save the injured