口蜜腹劍
A honey tongue, a heart of gall. ( be nasty-nice; Bees that have honey in their mouths have stings in their tails. )

久別情疏
Out of sight, out of mind. (Far from eye, far from heart. Long absent, soon forgotten. Seldom seen, soon forgotten.)

不告而別
French leave

不要不自量力
Don't put a quarter into a pint pot.

不要厚此薄彼
Don't make fish of one and flesh of another.

不畏艱難
Take the bull by the horns.

不戰(zhàn)而屈人之兵
The supreme art of war is to subdue the enemy without fighting.

不入虎穴焉得虎子
How can one obtain tiger-cubs without entering the tiger's lair.

不經(jīng)一事，不長(zhǎng)一智
Experience is the mother of wisdom.

不勝其煩
a pain in the neck：Your little brother is a pain in the neck. ?

小Car筆記：
nasty-nice：笑里藏刀的
French leave：悄悄離去，不辭而別。這個(gè)用法來(lái)自于18世紀(jì)法國(guó)風(fēng)俗，不通知主人而自己離開(kāi)。

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