They all tutoyer each other, even if they hate each other's politics, and they call each other by the informal name.

人们表面亲热,即使他们与对方的政见相对立,他们用非正式的名字称呼对方

耶鲁公开课 - 1871年后的法国课程节选

Well, that's pretty difficult. It, you know, I think it's easiest to do that in sort of an informal way.

分配起来确实挺困难的。你知道的，以一种非正式的方式反而更容易做到。

有趣的室友们 - SpeakingMax英语口语达人

And one thing I would strongly suggest is to form some sort of study groups, either formally or informally.

我强烈建议大家建立一些学习小组,正式的或非正式的都可以

耶鲁公开课 - 心理学导论课程节选

Legally, that's correct, but you see cases in letters and all kinds of stuff from the Ancient World that women actually were more unofficially part of their husband's house.

法律上是这样的，但是从古代书信,及其他各类文献中发现,女子更像是丈夫家中的非正式成员。

耶鲁公开课 - 新约课程节选

Right. Because all of us have probably bought something facebook on Amazon.com or the like, all of us have probably logged into Facebook.com, passing your credit card information over the Internet, passing your username and password over the Internet, and as you probably know, as a casual user, https denotes secure.

对的，因为我们都可能在亚马逊之类的网站上买过东西,我们都可能上过,在网络上传送你的信用卡信息,在网络上传送你的用户名和密码,你可能知道，作为一个非正式的用户，https保护安全。

哈佛公开课 - 计算机科学课程节选

But it's not at all unprofessional.

但这并不是完全非正式的用法。

Is it okay 课堂 - SpeakingMax英语口语达人