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Idle folks lack no excuses. 懒汉借口多 (来源：英语麦当劳－英语学习门户 http://www.EnglishCN.com)

An idle youth; a needy age. 少壮不努力，老大徒伤悲

Idleness is the key of beggary. 懒汉出乞丐

If a man once falls, all will tread on him. 墙倒众人推

If the mountain will not come to Mohammed, Mohammed must go to the mountain. 人事两将就

If the old dog barks, he give the counsel. 老狗叫，是忠告。

If there were no clouds, we should not enjoy the sun. 没有乌云， 就不只阳光的可贵。

If you run after two hares, you will catch neither. 脚踏两只船，必然要落空。

If two men ride on a horse, one must sit behind. 如果两人骑一匹马，总有一个人坐在后面。

If you don't aim high, you will never hit high. 目标不高，成就不大

If you sell the cow, you sell her milk too. 卖了奶牛就没有了奶

If you wish for peace, be prepared for war. 欲求和平，就得备战

I'll eat my hat if … 决无这回事；要是……我就不是人

Ill news travels fast. 坏事传千里 In a quarrel, both parties are to blame. 两人吵架，要怪双方。

In a breeze 轻而易举的

In a calm sea every man is a pilot. 风平浪静时，人人都可以当舵手。

In doing we learn. 在干中学

in high spirits 兴高采烈

in hot water 在困境中

in one's good books 受欢迎的

in the air 悬而未决的；人人都感觉到的

In prosperity think of adversity. 居安思危

in the same boat 同舟共济

in at one ear and out at the other 左耳朵进，右耳朵出

In every beginning think of the end. 未做一事，先思其结果

In every country the sun rises in the east. 太阳不分国别，永远升自东方。

In the long run 从长远的观点看

in one's mind's eye 在想象中

In the grave, the rich and the poor lie equal. 一朝入坟墓， 贫富无差别。

In water you see your face; in wine the heart of another. 水中可见自己的脸；酒中可知他人心。

In a word 总而言之

in the seventh heaven 在极乐世界

ins and outs 来龙去脉；细节

iron hand in a velvet glove 外柔内刚

It is easier to fall than to rise. 跌倒容易起来难

It is easy to be wise after the event. 事后诸葛亮好当

It is Greek to me. 一无所知。

It is hard to please all. 一人难讨百人心。

It is an ill wind that blows nobody good. 有利则有弊

It is easier to make enemies than to make friends. 结仇容易交友难

It is never too late to mend. 改过不嫌晚

It is never too later to learn. 活到老，学到老。

It is the first step that costs. 万事开头难

It is too later for the bird to scream when it is caught. 鸟被抓住才尖叫，为时以晚。

It never rains but it pours. 不下则已，下则倾盆。

It takes two to make a quarrel. 一个巴掌拍不响。