需知的英文：
need-to-know

need是什么意思：
v. 需要
n. 需要，必要；需要的东西；需求

We need to provide for everything we will need for the trip.
我们必须准备所有旅行要用的东西。

You need money and time, in addition, you need diligence.
你需要金钱和时间，此外你还需要努力。

Do you need to wee?
你要撒尿吗？

Need you go so soon?
你需要这么早走吗?

They need our help.
他们需要我们帮助。

know是什么意思：
v. 知道，了解，懂得；认识，熟悉；认出；体验；见到过，听到过

Learn not and know not
不学无术

Know/not know what is most important and act accordingly
能[不能]按轻重缓急行事

Do you know that lady?
你认识那位夫人吗？

Do you know the Hallelujah Chorus?
你知道哈利路亚合唱曲吗？

Few know and few care.
很少有人知道，也很少有人关心。