pay for的用法与搭配

Just as a matter of interest, how much did you pay for it?

我只是感兴趣，你这是花多少钱买的？

It seems unfair on him to make him pay for everything.

让他承担一切费用似乎对他不公平。

The reality is that there is not enough money to pay for this project.

实际情况是没有足够的钱花在这个项目上。

They pay for their children to go to a posh school.

他们花钱让子女上贵族学校。

The rail pass will pay for itself after about two trips.

火车月票大约只需乘两次车就够本了。