不败之地incincible position


不耻下问feel not ashamed to learn from one's subordinates


不可救药be past praying for beyond redemption


不劳而获reap where one has not sown


不屈不挠fortitude indefatigability perseverance persevere tenacity

不速之客crasher uninvited guest


不同凡响outstanding


不言而喻speak for itself tell its own story tell its own tale went without saying


不遗余力spare no effort spare no pains


不以为然not approve object to


不义之财filthy lucre filthy pelf the mammon of unrighteousness


不亦乐乎extremely


不远千里go to the trouble of travelling a long distance


不约而同happen to coincide


不择手段by any kind of means by hook or crook play hard by fair means or foul


不知所措be at a loss be all adrift lose one's head out of one's wits


才疏学浅have little talent and learning


惨绝人寰extremely cruel


沧海桑田time brings a great change to the worlds


沧海一粟/九牛一毛a drop in the bucket


草木皆兵a state of extreme nervousness


层出不穷emerge in endlessly


层峦迭嶂peaks over peaks


察言观色carefully watch what sb. is doing and saying


姹紫嫣红very beautiful flowers


畅行无阻checkless


车水马龙heavy traffic


沉默寡言taciturnity


称心如意well-content


趁热打铁strike while iron is hot Hold a wolf the iron is hot


成群结队gang horde


诚惶诚恐with reverence and awe


诚心诚意sincere desire


承上启下a connecting link between the preceding and the following


吃苦耐劳tough


中高级口译成语翻译精选2: http://insuns.com/article/18891-1.html