499　walk和on foot

1　walk 是不及物动词，意为“步行”，结构为：

walk+to+名词 (school, the hospital, the station)

walk+副词 (there, here, home)

They walked to the hospital . 他们步行到医院。

He walks home after school. 放学后他步行回家。

2　on foot 是介词短语，意为“步行”，用作状语或表语。

All of them are on foot . （正）他们都是步行的 。

All of them are on their foot . （误）

All of them are on feet . （误） （不用复数形式 ）