· keep one"s fingers crossed祈求成功

The leader was guilty of a serious dereliction of duty. He kept his fingers crossed that he could escape severe punishment.

· let something slip through one"s fingers眼睁睁地看着……跑掉

The lawyer studied the case very carefully. He wouldn"t let something slip through his fingers.

· build a fire under someone紧催促某人……

That guy is a slowpoke. I wish there were some way to build a fire under him.

put a fire under someone其主语一般是物，而不是人。

· have other fish to fry有其他要紧事要做

Come on out! Forget about the exam, You"re got other fish to fry.

· a flash in the pan昙花一现

He used to be called a young entrepreneur. But soon he was forgotten by the public. He was a flash in the pan.

· a fly in the ointment美中不足

Mobile phone are quite popular nowadays, but they ring at any time in the public areas. It is a fly in the ointment.

· be nobody"s fool不傻，精明

You can not easily take him in. It is obvious that he is nobody"s fool.

· get off on the right foot开门红

Everything will go smoothly if we get off on the right foot.

· put one"s foot down气愤的表示反对

The boy wanted to quit school, but his father put his foot down.

· play footsy with...与……调情

Jack was so in love with Mary that he couldn"t help playing footsies with her while having dinner.

· marry a fortune嫁给了有钱人

Scariet was in trouble, She wanted to marry a fortune and save the whole family.

· as sly as a fox非常狡猾

Though the suspect was as sly as fox, he had to admit his crime in front of solid evidence.

· a dime a dozen数不清，很多

Pagers were rare ten years ago. Now they are a dime a dozen.

· make free with...擅自使用……

Do you think I"m a millionaire? Don"t make free with my things.

· a freeloader白吃白喝，爱占便宜的人

In America, even if you live with your relative, you can"t be a freeloader.

· a fair-weather friend不能同患难的朋友

I have searched my conscience, and believe I have never mistreated you. But you turned out to be a fair-weather friend.

· get stage fright怯场，紧张

The student got stage fright when he stepped into exam room.

· add fuel to the flames火上浇油

The boy refused to make an apology to his father, which added fuel to the flames.