井井有条；井然有序
in apple-pie order
My wife likes to keep everything in apple-pie order.

 
少年老成；老成持重
have an old head on young shoulders
Michael has an old head on young shoulders and handles his business very well.

 
手足无措
not know where to put oneself/one's face
When I told Linda almost everyone at her department had seen the photo of her hugging and kissing her boyfriend affectionately in the street, she was so embarrassed she didn't know where to put herself/her face.

日复一日 (或一连数天)
day after day; day in day out (这亦可写成 "day in, day out")
It went on raining day after day.
If we do the same things day in day out, it isn't surprising we get bored.

附注：关于 "day after day"，其他表示时间的词也可以这样用，如 "year after year"，"month after month" 和 "night after night"；至于 "day in day out"，其他表示时间的词，尤其是表示较长时间的词，也可以这样用，如 "year in year out" (这亦可写成 "year in, year out"，以下亦同)，"month in month out"，"week in week out" 和 "night in night out"，但 hours, minutes 和 seconds 则不可以这样用。

 
日以继夜；夜以继日
day and night; night and day
He thought of her wife day and night when she went on business trip abroad last year.

 
日薄西山 (或好景不长)
someone's days are numbered
Now he knows his days are numbered.

 
五十步笑百步
the pot calling the kettle black
She was criticizing me for not looking for a new job but that is like the pot calling the kettle black. She isn't looking for a new job either.

 
太岁头上动土
beard the lion in his den (这里 "beard" 为动词)
My boss's in his office, so let's beard the lion in his den and ask for a pay raise.

中饱私囊
line one's (own) pocket/purse (with + money/profits)
The president's lack of oversight has allowed some of the Cabinet members to line their pockets with hundreds of millions of dollars.

 
心不在焉
here/there in body, but not in spirit; someone's heart is not in
I didn't understand very clearly what you said, because I was here in body, but not in spirit at the time.
John should try to find another job because his heart is always not in his work at all.

 
心满意足；痛痛快快
to one's heart's content (这个字的重音在第二音节)
It's weekend, so you can sleep to your heart's content.

 
心旷神怡
feel on top of the world
If health has been a problem, don't worry. You'll feel on top of the world from now on.

 
火上加油 (或煽动情绪)
add fuel to the flames/fire; fan the flames/fire
The workers weren't satisfied with their wages, so when they were asked to work longer hours, it added fuel to the flames.

火中取栗 (意为替别人冒险)
pull the/someone's chestnuts out of the fire
I had pulled the chestnuts out of the fire for him on several occasions and was unwilling to do it again.

 
方柄圆凿；格格不入
a square peg in a round hole
If you go to university, you will be a square peg in a round hole there because you just have no desire to study.

互相残杀；互相倾轧
cut each other's throats
For a bag of gold coins they would cut each other's throats without hesitation.

 
天涯海角
the ends of the earth
"Oh dear, as you know, I would take you to the ends of the earth at any time."

天壤之别；天悬地隔
be worlds apart
Our ways of life are worlds apart.
George and Mary decided to get married even though their families were worlds apart.

今日事今日毕
never put off till tomorrow what you can do today (亦写成 "never put off till tomorrow what may/can be done today"，但较少人使用)
It should be borne in mind that never put off till tomorrow what you can do today.

不自量力 (贪多嚼不烂)
bite off more than one can chew
I told him he would be biting off more than he could chew if he tried to get 950 points in the TOEIC test.

不言而喻 (或不用说)；不辩自明
go without saying; speak for itself/themselves
It goes without saying that I will never love  her.
The company has had a very successful year; the figures speak for themselves.

不念旧恶；宽大为怀
forgive and forget
We hated each other in Taiwan; we met again in the United States last year and decided to forgive and forget. Now we have become very friendly.

不相上下；半斤八两；铢两悉称
six of one and half a dozen of the other
Voting for a DPP or a KMT candidate is a case of six of one and half a dozen of the other.

不动声色；泰然自若
keep one's countenance; play it cool
Most people could hardly keep their countenance in the face of death.
They expected us to be angry, but we had decided to play it very cool.

不知所措；晕头转向
at a loss; lose one's bearings; not know whether one is (standing) on one's head or one's heels
When she asked me if I had ever divorced any women, I was at a loss for words. ( at a loss for words：无言以对)
In all this mass of details I'm afraid I've rather lost my bearings.
When his shop was very busy yesterday morning, the poor shopkeeper didn't know whether he was on his head or his heels.

不屈不挠
(keep one's) chin up
He's having a pretty difficult time but he seems to be keeping his chin up.

不择手段；千方百计
by hook or by crook; stop at nothing (to do something)
David is trying to get that promotion by hook or by crook; he even spread rumors smearing the other candidates.
The young man wanted to be rich and would stop at nothing to get more money for himself.

不入虎穴，焉得虎子
nothing venture, nothing gain/win/have (or "nothing ventured, nothing gained")
"Nothing venture, nothing gain", as the saying goes.