A lot __to save the old man's lifeA have been done B has been done

问题描述:

A lot __to save the old man's life
A have been done B has been done

B

A have been done
a lot 复数
请采纳

B
a lot可以跟可数名词复数,也用跟不可数名词,象这种单用作主语的"很多"本身是不可数名词,所以后面用谓语单数