—How are things getting on?—All that can be done____.

问题描述:

—How are things getting on?—All that can be done____.
A.has been done B.have been done C.has done D.have done

A
事情进行得怎么样?---所有能做的事情都完成了
答句中的all that can be done-----这又作为答句的主语
all修饰that,没有出现复数形式,所以用has all that=what,
谓语部分用 has been done(被动,事情是被完成)