Idle people (folks) have the most labour (take the most pains).懒人做工作，越懒越费力。
Idleness is the key of beggary.懒惰出乞丐。
Idleness is the root of all evil.懒惰乃万恶之源。
If a job's worth doing, it's worth doing well.
If you want knowledge,you must toil¹ for it.若要求知识，须从勤苦得。
If you would have a thing well done,do it yourself.想把事情来做好，就得亲自动手搞。
Ignorance is bliss².
Ignorance of the law excuses no man.
Ill news travels fast.恶事传千里。
In for a penny,in for a pound.做事一开头，就要做到底；一不做，二不休。
Industry is fortune"s right hand,and frugality³ her left.勤勉是幸运的右手，世俭是幸运的左手。
It is good to learn at another man"s cost.前车可鉴。
It is ill to waken sleeping dogs. [let sleeping dogs lie; don"t wake a sleeping dog.] 别多事, 别惹麻烦。
It is in to be on the safe side.
It is lost labour to sow where there is no soil.没有土壤，播种也是徒劳。
It is no use crying best spilt milk.
It is not work that kills,but worry.工作不会伤身，伤身乃是忧虑。
It is right to put everything in its proper use.凡事都应用得其所。
It never rains, but it pours.
It rains cats and dogs. 下倾盆大雨, 大雨滂沱
It takes two to tango.
It is no good crying over the spilt milk. 覆水难收。
It takes two to make a quarrel.一只碗不响。
Jack⁴ of all trades, master of none.
Keep your mouth shut and your ears open.
Kill two birds with one stone.一箭双雕。
Knowledge advances by steps and not by leaps.知识只能循序渐进，不能跃进。
Knowledge is power.知识就是力量。
Laughter is the best medicine.
Lead a dog's life 过着牛马不如的生活
Lead a dog's life 过穷困潦倒的日子
Learn wisdom by the follies⁵ of others.从旁人的愚行中学到聪明。
Let bygones be bygones.
Let sleeping dogs lie.
Let the buyer beware.
Let the cat out of the bag 说走了嘴, (无意中)泄露秘密
Let the dead bury their dead.
Let sleeping dog lie. 不要惹是生非。
Let's call a spade a spade.直言不讳。
Life is just a bowl of cherries.
Lightning never strikes twice in the same place.
Like a cat on hot bricks 局促不安, 如热锅上的蚂蚁
Like father, like son.
Like mother, like daughter.
Live and learn.
Live like cat and dog [口]整天吵架
Live a cat and dog life（夫妻）过着不和谐的生活（误：过着猫和狗一般的生活）
Living without an aim is liking⁶ sailing without a compass. 生活没有目标等于航行没有指南针。
Look after number one.
Look on the bright side.
Look before you leap.三思而后行。
Lookers-on see most of the game. 旁观者清。
Love conquers all.
Love is blind.
Love makes the world go round.
Love me, love my dog. 你若把我当朋友, 也要把我的朋友当朋友; 爱屋及乌。
Love sees no faults.
Love will find a way.
Love me, love my dog.爱屋及乌
Make hay while the sun shines.晒草要趁太阳好。
Man cannot live by bread alone.
Many hands make light work.众擎易举。
Many hands make quick work.人多干活快。
Many a little makes a mickle.积少成多。
Many hands makes light work. 人多好办事。
Marriages are made in heaven.
May As soon as man is born he begins to die.
Might is right.
Mind your own business.
Money is the root of all evil.
Money isn"t everything.
More haste, less speed.欲速则不达。