中文里有俗语“天下没有免费的午餐”，英文也有，那就是free lunch。free lunch指“不费力或者不付出代价就能白白获得的东西”。

例句：

There is no such thing as a free lunch.

天下没有白吃的午餐。

He'll hardly offer you a job if you don't contribute to his party; there's no free lunch in political campaigns.

如果你没有为他的党派做出什么贡献，他应该不会给你一份工作的；毕竟在政治活动中可没有白吃的午餐。