(欢迎大家补充，一起来学外语)
得寸进尺：You give him an inch and he'll take a mile
爱屋及乌 Love me, love my dog.
百闻不如一见 Seeing is believing.
半斤八两 six of one and half a dozen of the other
班门弄斧 teach fish to swim; teach one’s grandmother to suck eggs
本末倒置 put the cart before the horse
捕风捉影 catch at shadows
不顾艰险，赴汤蹈火 go through thick and thin; go through fire and water
不可外扬的家丑；隐情 a skeleton in the cupboard
不浪费，不愁缺 Waste not, want not.
不伦不类；非驴非马；古怪之人 be neither fish,flesh,nor good red herring
不劳则无获 No pains, no gains. No gains without pains.
不入虎穴，焉得虎子 Nothing venture,nothing have.
吃一堑，长一智 A fall into the pit, a gain in your wit.
出生牛犊不怕虎 A new-born calf makes little of a tiger.
船到桥头自会直 You will cross the bridge when you get to it.
打草惊蛇 beat the grass to alert/startle the snake
大海捞针 look for a needle in a haystack
打开天窗说亮话 put all cards on the table
(他)得寸进尺 Give him an inch and he’ll take an ell.
多此一举 carry coals to Newcastle
洗心革面 turn over a new leaf
放长线，钓大鱼 throw a long line to catch big fish
改邪归正 mend one’s ways
隔墙有耳 Walls have ears.
本性难改 The leopard can’t change its spots.
孤注一掷 put all one’s eggs in one basket
光明正大 be fair and square
过河拆桥 kick down the ladder上楼抽梯
画蛇添足 paint the lily
患难见真情A friend in need is a friend indeed.
浑水摸鱼 fish in troubled waters
火上加油 add fuel to the fire; pour oil on the flame
既往不咎 Let bygones be bygones.
见风使舵 (to steer according to the wind)
骄兵必败 Pride goes before a fall.
捷足先登 The early bird catches/gets the worm.
金窝银窝，不如自家草窝 East or west, home is the best.
酒肉朋友 a fair weather friend
不择手段 by hook or by crook
来得容易，去得快 Easy come, easy go.
乱七八糟 be at sixes and sevens
旁观者清 The onlooker sees most of the game.
破釜沉舟 burn one’s boat
骑虎难下 hold a wolf by the ears
巧妇难为无米之炊 One can’t make brick without straw.
入乡随俗 When in Rome, do as the Romans do.
山穷水尽 be at the end of one’s rope(tether)
三思后行 Look before you leap.
事难两全 You cannot eat your cake and have it
食言 go back on one’s word
水底捞月 fish in the air
熟能生巧 Practice makes perfect.
捡了芝麻，丢了西瓜 Penny wise, pound foolish
胸有成竹 have a card up one’s sleeve
雪中送炭 help a lame dog over a stile
易如反掌 as easy as a turn of one’s wrist
英雄识英雄 Like knows like.
英雄所见略同 Great minds think alike.
欲速不达 More haste, less speed.
掌上明珠 the apple of one’s eyes
直言不讳 call a spade a spade
坐立不安 be/sit on pins and needles