I guess most people think thirty years is long enough, but that's the way mortgages go ever since.

我猜大多数人都认为30年足够长了,这是抵押贷款的演变过程

耶鲁公开课 - 金融市场课程节选

Adjustable rate mortgages have a long term -they might last for thirty years -but the interest rate is not fixed for the whole thirty years.

可调利率抵押贷款的期限很长,也许会长达30年,但是利率在30年间并不是固定的

耶鲁公开课 - 金融市场课程节选