at someone's back

in pursuit or support someone

追求；支持（某人）

back and forth

to and fro

來回地

back in the day

in the past; some time ago

在過去，在以前

back in the day, he'd had one of the greatest minds I'd ever come across.

從前他曾是我所遇到過的最有頭腦的人之一。

someone's back is turned

someone's attention is elsewhere

某人的注意力在別處

he kissed her quickly, when the landlady's back was turned.

趁女房東注意別的地方的時候，他很快地吻了她一下。

the back of beyond

a very remote or inaccessible place

偏僻處

back o'Bourke

(Austral. informal)the outback

(澳，非正式)內地

the back of one's mind

used to express that something is in one's mind but is not consciously thought of or remembered

下意識里

she had a little nagging worry at the back her mind.

下意識里她還存有顧慮。

back to front

(Brit.)with the back at the front and the front at the back

(英)前后顛倒

the exhausts had been fitted back to front.

排氣管前后裝倒了。

a back-to-front baseball cap.

前后顛倒的棒球帽。

back water

reverse the action of the oars, causing a boat to slow down or stop

倒槳

back the wrong horse

make a wrong or inappropriate choice

下錯了賭注；做錯了選擇

behind someone's back

without a person's knowledge and in an unfair or dishonourable way

在某人背后，背著某人

Carla made fun of him behind his back.

卡拉在他背后取笑他。

get (或 put) someone's back up

make someone annoyed or angry

惹惱（或惹怒）某人

in back

(N. Amer.)at the back of something, especially a building

(北美)在后面（尤指建筑）

dad demolished an old shed in back of his barn.

父親拆掉了倉庫后面的一個舊棚。

know something like the back of one's hand

be entirely familiar with a place or route

（對地方或路線）了如指掌