they are going to have breakfast.

问题描述:

they are going to have breakfast.
这句 是 :他们准备吃早餐 还是 他们正在吃早餐
我不是很清楚
请列出这两个句子的区别 怎么区分 准备做和正在做某事的区别

they are going to have breakfast.是他们准备吃早餐
be going to =will表示将要
they are having breakfast.是 他们正在吃早餐
be doing sth 是正在做某事