If only I knew her name.

我要是知道她的名字就好了。

《牛津词典》

Your mother would have a fit if she knew you'd been drinking!

要是你母亲知道你一直喝酒，会很生气的！

《牛津词典》

He called Amy to see if she knew where his son was. As it happened, Amy did know.

他打电话给埃米，看她是否知道他儿子在哪儿。碰巧的是，埃米还真知道。

《柯林斯英汉双解大词典》

No one knew if they could get the spacecraft back to Earth, or if they could survive long enough to return.

VOA: special.2009.07.22

And, we knew that if we know the crystal structure we can get the Madelung constant, not a problem.

我们都知道只要有了晶体结构,就能知道马德隆常数。

麻省理工公开课 - 固态化学导论课程节选

If you knew only the third derivative of the function, you can have something quadratic in t without changing the outcome.

如果方程里有三阶导数,你就可以引入一个二次项,但是结果却不会变

耶鲁公开课 - 基础物理课程节选

If Jonny knew what he was going to do, if we knew what he was going to do and if the Australians knew what he was going to do - why didn't someone jump on him before he got the ball?

BBC: SPORT | Rugby Union | Rugby's laws remain baffling

It alleges he committed three counts of perjury, accusing him of lying twice when he was asked if he knew specific people and he denied knowing them and once when he was asked if he knew one of those people had been on a certain committee and he said he didn't.

WSJ: Politician indicted in NY 2008 perjury case

She asked if officers knew if the takeaway had closed down or moved.

BBC: Toilet roll 999 call made to Devon and Cornwall Police