For those of you not in the know, the game is all about math skills.

对于你们那些不知情的人来说，这款游戏完全关于数学技能。

Somebody in the know told me he's going to resign.

有知情者告诉我他要辞职了。

It was gratifying to be in the know about important people.

了解重要人物的内幕令人满足。

Persons in the know also revealed some malpractices at the fair.

知情人披露了一些交易会上的不正之风。

But today, all the kids in the know use Club Penguin.

但是今天，所有的孩子都知道企鹅俱乐部。