have 是用餐和吃饭,强调整个吃饭的笼统过程,多用于短语中.
eat 很多时候,强调吃这个动作,就是强调把东西放进嘴,这个动作,略微表
示进行时的倾向.
have breakfast/lunch/dinner/breaklunch
She is eating a late lunch.
She had eaten a shit .
就这一点点区别,混用没什么大问题.