The senators are targeting provisions in a law that governs how companies' foreign income is taxed.

参议员们的目标是制定一项管理公司海外收入如何征税的法律条款。

And one way it's doing that is by blocking Iran's revenues from oil sales, which are the main source of the country's foreign income.

其中一种做法是阻止伊朗从石油销售中获得收入，而石油销售是伊朗国外收入的主要来源。