不屑一顾to disdain as beneath contempt

不言而喻obvious

不约而同a coincidence;taking the same action without prior consultation

不择手段by fair means or foul;by hook or by crook;unscrupulously

不知所措not knowing what to do;refers to an awkward or confusing situation

不自量力overrate one’s own abilities

三言两语just a few words

草木皆兵imaginary fears (lit. every tree or bush an enemy soldier)

参差不齐non-uniformity;non-standard

层出不穷more and more emerge;innumerable succession;breeding like flies