過去的、過期的

back number：專指過期的雜志期刊

It doesn't matter. It was a back number anyway.

沒關(guān)系，反正都是過期的雜志。

拖欠、積欠的

a back pay/rent/taxes

He was unemployed and owed 2 months'back rent.

他失業(yè)了且欠了兩個月的房租。

The boss must provide back rent with workers.

老板必須把積欠的工資支付給員工。

at the back of 

背后的原因

Could you feel anything at the back of it?

你知道這里面的名堂嗎？

at the back of mind

內(nèi)心所想，但不是很確定的東西

I have an idea at the back of mind that I met him somewhere.

我好像記得似乎在哪里見過他。

be one's back

依靠某人

He must be his back because he has no choice.

他必須依靠他因為別無他法。

turn one's back on

①把背轉(zhuǎn)向他人，形容不理睬別人，衍伸為拒絕他人

I turned to him for help ,but he turned his back on me.

我向他求助，但他不愿搭理我。

②背棄、放棄

She turned her back on what she insisted

她放棄了一直以來所堅持的。

behind one's back

瞞著別人；背著別人做某事

We should not speak ill of a man behind his back, which is impolite.

我們不應(yīng)該背地里說別人的壞話，這是不禮貌的。

take a back seat

退居二線、次要地位；知趣靠邊站

The senior took a back seat and made room for the young and new ideas.

長者退居二線讓位給年輕人和新思想。

back and forth

前前后后，來來回回

The wind moved the twigs gently back and forth.

風(fēng)輕輕地吹著樹枝來回搖晃。

there and back 

往返，來回

Can I go there and back in one day？

我一天內(nèi)來回趕得了嗎？

其他常見短語：

break one's back（全力以赴）

back down(退出)

answer back（頂嘴）

bring back to health(恢復(fù)健康)

come back(回來；重新流行；想起來)

hand back (物歸原主）

pay back(還清）

sit back (袖手旁觀）

win back（重新贏回）

turn back(折回；往回走）

run/roll back(倒帶）

bite back(很快抑制自己，沒有說出不該說的話）

Not to advance is to go back

不進則退