A perpetuity is an asset or a contract that pays a fixed amount of money each time period, forever.

永续年金是一种财产或者合同,规定在每一时间段内,支付一定数量的货币,直至永远

耶鲁公开课 - 金融市场课程节选

Well if you have a slave, that slave can't actually sign contracts.

如果你有一个奴隶，但法律规定奴隶不能签署合同。

耶鲁公开课 - 新约课程节选

They have a labor contract that specifies how much they will get.

他们之间的劳工合同规定了工资的多少

耶鲁公开课 - 金融市场课程节选

And so if you sign a contract with the government for millions of dollars, you have guarantee to get your dollars back, plus whatever profits they allowed in the contract.

所有如果你和政府签订了合约,做了一个百万的大单子，你能保证拿到钱，和其他的利润,在合同里规定的利润。

斯坦福公开课 - 经济学课程节选

If you buy a house and you don't pay the mortgage, the contract says you lose the house-- you're out--you've got to pay or it goes back to the mortgage originator.

如果你抵押贷款买房,却没有还房贷,贷款合同规定,你将被取消赎回权,失去房子,所以你必须偿还贷款,否则你的原始贷款人就会收回房子

耶鲁公开课 - 金融市场课程节选