我的新鞋子很舒服，走了一整天脚都不疼。

My new shoes are so comfortable that my ___feet don't hurt even after walking all day.

这条河大概有50英尺深。

The river is about 50 ___feet deep.

我们在大楼的底部发现了一个秘密入口。

We found a secret entrance at the ___foot of the building.

这首诗每行有三个音步。

This poem has three ___feet in each line.