I don't know if he's telling the truth or not.

我不知道他是否说了真话。

《牛津词典》

She does not know if he is alive or dead.

她不知道他是活还是死。

《柯林斯英汉双解大词典》

You do not know whether what you're told is true or false.

你不知道别人告诉你的是真的还是假的。

《柯林斯英汉双解大词典》

In a poker game you do not want to let your opponents know if your cards are good or bad.

VOA: special.2009.11.22

to the process whereby the heavenly angels not only eat food but they also digest it; and Milton lets us know, whether we want to know or not, how those angels actually excrete the food they have taken in.

去描述天堂的天使不只吃食物而且要消化它的过程,弥尔顿让我们知道，不管我们想不想，这些天使怎样排泄出他们吃的食物。

耶鲁公开课 - 弥尔顿课程节选

The heroine of the mask, as you know, doesn't seem to have a Christian name. She's not Britney or Lindsay.

你们也知道《面具》里的女主角，似乎没有教名，她不是布兰妮或林赛。

耶鲁公开课 - 弥尔顿课程节选

And all the while the American dream shrivels and Obama seems either not to know or not to care.

FORBES: Competency, Not Ideology, Is What Will Determine The Election

YouTube was able to build a business based largely on content it did not own, did not license, and did not know whether or not was infringing.

FORBES: How the Second Circuit's Decision in Viacom May Change the Web

Did you not know or should you not have known then (now) about the health risks associated with your cell phone use?

FORBES: Cell Phone Radiation? Text, Don't Talk, advises FCC