play dumb with someone装聋作哑
Its no use playing dumb with teachers. They know very well their students.
be down in dumps垂头丧气，深情沮丧
I burned midnight oil yesterday. So I feel down in the dumps today.
make the dust fly干得非常起劲
Many volunteers are helping1 in the Olympic Games. They are making the dust fly without getting pay.
go easy on...酌情处置；节省用；对手下留情
I hope the teacher will go easy on me. Otherwise, Ill have no chance to pass the exam.
当介词on的后面跟得是something的时候，此语用来是节省用或小心对待
Go easy on salt. We have to save some for the next meal.
egg someone on to do something怂恿，鼓动某人干某事
Havent you seen him through? He can help you nothing but egg you on to do illegal things.
rub elbows with someone和某人没非常深的交情
I suppose Jack2 doesnt know me well. We have only rubbed elbows with other for several times.
be at the end of ones tether山穷水尽
Mark feels worried because he cant write any new books. He is afraid that he is at the end of his tether.
be at ones wits end不知怎么样是好
My boy is such a mischief-maker. I am at my wits end with him.
be at loose ends心里没着落
Many old people feel at loose ends after their retirement3.
make both ends meet收入支出平衡
The newly-wed couple found it hard to make both ends meet.
be green with envy羡慕极了
Dont be green with envy. He deserves the prize, since he has spent a whole month on that paper.
be of the essence绝对不可少，重点的
As for study, diligence is of the essence.
a poor apology for...蹩脚货，名不副实
That travel agency was first-class, but it offered a poor apology for its service
make an exhibition of oneself出洋相
假如表示总出洋相可以在exhibition一词前加上形容词， regular
She is a bit insane. She always makes a regular exhibition of herself by raging at almost everybody.
keep an eye open密切注视
Keep an eye open for anyone who arouses your suspicion.