赴汤蹈火
go through fire and water
I will go through fire and water to help my relatives and friends.
　
风平浪静；水平如镜
(as) calm as a millpond; like a millpond
The Dead Sea is normally as calm as a millpond./The Dead Sea is normally like a millpond.
　
既往不咎(过去的事就让它过去吧；尽弃前嫌)
let bygones be bygones
Despite the fact that her father treats her very badly, she has decided to let bygones be bygones and take care of him when he is too old.
　
怒气冲天；大发雷霆
go up in the air (参见「大发雷霆」-- do one's nut)
My girlfriend went up in the air because I had a date with another girl.
　
美中不足
a/the fly in the ointment
I've been offered a wonderful job, but the only fly in the ointment is that the pay is not too good.
　
洗心革面；改过自新；重新做人
turn over a new leaf
I've decided to turn over a new leaf and find a good job.
　
省吃俭用
pinch and scrape
I have to pinch and scrape in order to save enough money to visit my parents in Japan next year.
　
信口开河；胡说八道
talk through one's hat
He says he knows genetics very well, but he's talking through his hat!
　
英雄所见略同
great minds think alike
A: "I was just thinking to call you, then the phone rang and it was you calling me."
B: "Great minds think alike."

A: "This summer I've decided to take scuba diving lessons."
B: "Really? Me too. I have already paid for the course."
A: "Great minds think alike."

首屈一指；独占鳌头；出类拔萃
bear (or carry off) the palm
Students of this university bear the palm in the international landscape designing contest.

神色自若；泰然自若；不动声色
not turn a hair
When someone we fear passes near, it makes our hair stand on end, no matter how much we try not to turn a hair.

恨之入骨
hate like poison
They hate each other like poison.
The teacher was hated like poison by all his students.

飞黄腾达
make it big; fly high
"Believe me! I am going to make it big myself one day."
He began flying high when he got married to his wealthy wife.

指名道姓(说出做坏事者或违法者的姓名)
name names
She swears she will never name names, even if she were offered a reward.

胡说八道
stuff and nonsense!
Stuff and nonsense! I never said that sort of thing.

怒目而视
look daggers at
I suddenly noticed my wife looking daggers at me and thought I'd better shut up.

屏息以待(或屏住呼吸)
hold one's breath
I held my breath and waited to see if my name had been called for an interview with the movie company.
The movie was so horrible that everybody held his breath.

厚此薄彼
make fish of one and flesh of another
Don't make fish of one and flesh of another in treating your children.

咬牙切齿
gnash one's teeth
The man gnashed his teeth when he saw his wife going on a date with another man.

咬紧牙关
grit one's teeth
One has to grit one's teeth during difficult times.

秘而不宣；守口如瓶
keep one's (own) counsel; play/keep/hold one's cards close to one's/the chest (参见「守口如瓶」-- keep a quiet/still tongue)
he's known to keep his counsel and not prematurely reveal his position on some sensitive issues.
With reference to the reasons for his unexpected promotion, he always plays his cards close to his chest.

挑三拣四；挑挑拣拣
pick and choose (注意：pick 和choose 的顺序不可对调)
There are just too many new houses in the city for us to pick and choose.

挑灯夜战；开夜车
burn the midnight oil
The semester is almost over and we're all burning the midnight oil before exams.

为所欲为
get away with (blue) murder
Some well-placed people in Taiwan can indeed get away with blue murder!