I only know one of them.

我只认识其中一个。

youdao

I only know one thing, and that is what all don't know.

我只知道一件事，那就是什么都不知道。

youdao

I only know one: If you feel a little scared or apprehensive, you ‘feel nervous’, even ‘nervy’.

我只知道一个意思哦：如果你受到惊吓或者觉得不安，你会“感到紧张”，甚至有点“神经质”。

youdao

You know, one of the things that I say and only half ingest, is that I know of no more selfish act and a benevolent act.

我说到的一件事，只说了一半意思，即最自私的所为就是善举。

哈佛公开课 - 幸福课课程节选

I mean, you only got one vehicle for life so if you put your body away, you know,

我是说，人一生就这么一个身体，要是身体没了，

成为教练的理由 - SpeakingMax英语口语达人

In the case of my friends, at least, I only know maybe one person who is vocally upset at From for the drawbacks that have come up over time.

FORBES: Connect

In other words, I know only one word, and that word is yes, and yes to everything.

CENTERFORSECURITYPOLICY: Center For Security Policy

In my local Seattle area, I know of only one and it is very popular: Metrix:CreateSpace.

FORBES: Connect