A lot (has been done)to save the old man's life

问题描述:

A lot (has been done)to save the old man's life
A lot (has been done)to save the old man's life.为什么要这样填

本句意思是:医生已经想尽各种办法去抢救老人的生命.显然结果是老人已经死了.判定为过去式,a lot 是代表数量的词.用单数.has