before you can say knife

(informal)very quickly; almost instantaneously

(非正式)極快地，立刻

(that) one could cut with a knife

(of an accent or atmosphere) very obvious

（口音，氣氛）非常明顯的

get (或 stick) the knife into (或 in) someone

(informal)do something hostile or aggressive to someone

(非正式)加害某人，跟某人過不去

go (或 be) under the knife

(informal)have surgery

(非正式)做手術(shù)

the knives are out for someone

(informal)there is open hostility (towards someone)

(非正式)（對某人）劍拔弩張

like a hot knife through butter

very easily; without any resistance or difficulty

輕而易舉；勢如破竹

anti-aircraft fire would slice through the car like a hot knife through butter.

防空火力將輕而易舉地把汽車打成碎片。

twist (或 turn) the knife (in the wound)

deliberately make someone's sufferings worse

故意讓人更加痛苦，揭人瘡疤

under the knife【非正式用語】

Undergoing surgery.

進行外科手術(shù)