Very few of you.

几乎没有吧
Why do you manage to get some cooperation

为什么即便没有书面合同
between you and your roommates even without a written contract?

你一样可以和你室友合作得愉快
It's not legally enforceable.

它不具有法律强制性
Well it probably is legally enforceable actually.

事实上它具有法律强制性
This guy says not, but it probably is legally enforceable.

这个男生说没有但它确实有
He probably could have a written contract about tidying up.

你们可以写个书面协议
The woman in here.

请那位女士回答
Repetition; you do it over and over.

重复你一遍又一遍地重复
Yeah, so maybe even among your roommates, maybe you don't need a contract

没错就算你和室友没有书面协议
because you can manage to achieve the same ends,

你们一样能达到预期的目的
by the fact that you're going to be interacting with the same person,

因为在耶鲁大学上学期间