具体指脚时或英尺时的复数,就用feet
如
How many feet do you have?
I have two.
He is 6 feet tall.
foot:用在短语中或构成一些词:
如
on foot步行,也可用with feet(但不是步行,而是用脚的意思),但不用with foot的
football;
footprint脚印
如
I often go home on foot.
Punching with fists and kicking with feet are allowed in taekwondo.
跆拳道允许用拳击和用脚踢。
foot是单数,feet是复数
on foot和by bus 等是一样的,交通方式,跟语法没关系
因为on foot是一个固定词组