Do not boast about tomorrow, for you do not know what a day may bring forth.

不要为明日自夸，因为一日要生何事，你尚且不能知道。

youdao

The truth is, you do not know what you are born with until you try very hard to express it.

事实是，你并不知道自己与生俱来的才能，直到你非常努力地尝试把它们表现出来。

youdao

You do not know what he really is; then pray do not pain me by speaking of him in such terms.

你不了解他真正的为人，因此，我求你不要这样编派他，免得我痛苦。

youdao

You monkey around with something when you do not know what you are doing.

VOA: special.2011.03.13

Usually when you know why it's not working, it's obvious what you have to do to make it work.

通常你明白了出错的原因后，很明显你必须让程序正常运行起来。

麻省理工公开课 - 计算机科学及编程导论课程节选

Unless you tell them what to do they're not gonna know how to do it.

除非你告诉它要做什么,它自己是不知道做什么的。

哈佛公开课 - 计算机科学课程节选

You need to learn them if you do not know what they are.

FORBES: Annual Performance Review: Time Suck or Amazing Opportunity

The difficulty comes when you do not know what garbage looks like.

ECONOMIST: Statistics and climatology

Here is that secret first step: If you have no experience selling anything to Chinese people or organizations in actual China, admit that you do not know what you are doing.

FORBES: Want To Sell To Chinese Customers? The Secret First Step