He said he did not know.

他说他不知道。

Who do not know each other?

谁不认识对方？

I did not know who she was.

我不知道她是谁。

They did not know what a computer looked like.

他们不知道电脑是什么样子的。

The scientists did not know why the penguins were lost.

科学家们不知道这些企鹅为什么迷路了。

He does not know whether they will plant trees on Saturday or not.

他不知道他们周六是否会去植树。

But they could not help him because they did not know what kind of snake bit him.

但他们无法帮助他，因为他们不知道是什么蛇咬了他。

We do not know how circuses will develop in the future.

我们不知道马戏团未来会如何发展。

You may not know over 30% of the world's food is wasted.

你可能不知道世界上超过30%的食物被浪费了。

I did not know I had stowed away on such an important one.

我不知道我偷渡上了这么重要的一次航行。