He had always been open with her and she always felt she would know if he lied.

他对她一向很坦诚。而她也一直觉得如果他撒谎了，她是会知道的。

《柯林斯英汉双解大词典》

How he would know, I love him.

他肯定能感受到，我有多么爱他。

youdao

If he had read as much, he would know as little.

如果他读得很多，却知道得很少。

youdao

In other words, he would know what the children are doing even when he is not watching them.

VOA: special.2009.09.06

If he had read as much, he would know as little.

如果他读得很多，却知道得很少。

耶鲁公开课 - 政治哲学导论课程节选

Sure, if my son would wake up and I didn't tell him, he wouldn't know that it was duplicate.

当然，如果我儿子醒来,可我还是没告诉他，他不会知道这塔是重新搭的。

耶鲁公开课 - 死亡课程节选

They believe he was the one who wrote it because there were details in it only he would know.

NPR: Massive Manhunt On For Ex-Cop Accused Of Killing 3

He would know it because he once lived it, and he fixed it.

FORBES: Ronald Reagan Would Not Be Fooled By Today's Presumptions of Low Inflation

You might note that Mr. Mohamed was a certified appraiser so you might think he would know what to do.

FORBES: No Appraisal No $18.5M Deduction, Says Tax Court