You never know how he is going to react.

你根本不知道他会作何反应。

《牛津词典》

You never know what to expect with her. She's so temperamental.

你永远说不清她要干什么。她一时一变。

《牛津词典》

Louis Armstrong said, if you've got to ask, you'll never know the answer.

路易斯·阿姆斯特朗说过，如果你一定要问，你将永远都不会知道答案。

youdao

So I've never felt like a minority because,as you know, minorities are never supposed to say anything unkind about one another."

VOA: special.2010.08.08

To put it differently, in order to know what "Dogs" means, you never had to learn the word "Dogs."

换个说法,为了知道"狗狗们"的意思,你不需要去学"狗狗们"这个词

耶鲁公开课 - 心理学导论课程节选

Because what we want to know is what is like to be permanently dead, and these people were never permanently dead.

因为我们想知道的是,永久死去是什么样的,而这些人并没有永久地死去

耶鲁公开课 - 死亡课程节选

By the way, these are lessons that stage parents, whether sports or pop music, never seem to know, and never seem to learn.

FORBES: Rebecca Black, and the lessons for sports parents

Yes, Mary gave birth to her first son -- a child who will never get to know his father.

CNN: Top 5 lessons from the 'Downton Abbey' season finale

When the service was over, he got in his vehicle and he drove back, never attempting to be noticed, never seeking that to know, as my deceased wife used to say, the real measure of generosity is would you do it and no one ever knew you did it.

WHITEHOUSE: Remembering Senator Robert Byrd