~~~should do it

问题描述:

~~~should do it
书上有个2个句子
问 :How much honey do we need ?
答:Two cups should do it.
请问这里的should do it怎么理解?
用法是怎样的 ?最好有例句!

就是Two cups will do.(两杯就行了.)
再如How many exercise books do you need?
Two will do.
前面要用名词或动名词,
就是do的一种万能词的用法吧.