buy sb's silence

买下某人的沉默，意思就是“（做某事或付款以）封住…的嘴”。

例句：

What will we have to do to buy her silence?

我们要怎样才能封住她的嘴？

buy the story/excuse

buy还有“接受，相信（尤指不太可能真实的解释或理由）”之意，常接story或excuse等。buy into sth也可表示“相信（某种观点）”。

例句：

She'll never buy that story about you getting lost!

她永远不会相信你迷路的事！

She'll never buy that excuse.

她怎么也不会相信那个借口的。

A lot of women have bought into the idea that they have to be thin to be attractive.

许多女人都深信要想迷人必须苗条。