I know the word.
(implies you have a deeper understanding of the word's meaning)

I know why he left.

I don't know where Ralu went.

I know why she isn't here.

If you saw my sister, you'd certainly know she was pregnant.

I know that his failure disappointed you greatly.

I know you hate him, but vengeance is not a proper response.

I know one thing: Wherever we go, this family is our fortress.

It's not known whether this heavy boat will float or sink.

A: Have you heard that Ralu has the hots for Tsenu?
B: Old news, brother! I've known it for a week.

If you don't know, ask me.

One night, while a young man named Ìstaw had the watch at the border of his country, he suddenly heard a strange unexpected noise in the forest. He knew that there was no viperwolf pack nearby. But as a matter of fact he was familiar with every animal cry of the forest; therefore he knew that this cry had come from a Prolemuris. He decided to carefully step to the source of the sound.

In the meantime, brothers and sisters, please follow the new guidelines and rules. Stay home as often as possible. Wash your hands many (times a day). Keep back a bit from other people. And if you know older folks, whether in your family or as friends, contact them to find out if they're well.

A: What are these things?
B: I don't know, but don't touch them! They look dangerous.

Yes, the Skypeople love exploration, but they don't know what to do once they find something.

As you know, during the Avatar Community Meet-up in Los Angeles last month, all the participants came to our house one evening to have dinner, study a little Na'vi, hang out together, and have fun. For John and me, that evening was a real treasure.

Pretty bad. He understands almost nothing and only knows eight words.

My crossbow has mysteriously disappeared. I don't know where it is.

Akwey spoke to Tuke confidently, knowing that she couldn't refuse.

I don't know where they're going.

That night beneath the trees when she looked at me meaningfully, I knew by the expression on her face that she loves me.

I See you, my friends, and I thank you. I have heard the message you have sent me so passionately. I feel your love for the Na'vi language. And I know you are all waiting for my guidance.