they are go to school on foot.为什么不对,为什么要用they are going to school on foot.

问题描述:

they are go to school on foot.为什么不对,为什么要用they are going to school on foot.

一句话中的“时态”是根据动词的形式而决定.
they go to school .现在时
they are going to school (be动词+现在分词=>进行时)
are go 不能两个动词连着使用.