1.knife用作名词时意为“刀”,转化成动词则指用刀将某物割开或把刀刺进某物之中,即“切割,刺”,这种动作通常是一种伤害性的动作,其宾语多为人。
2.knife多用作及物动词,后接名词或代词作宾语。可用于被动结构。

knife through(v.+prep.)
穿过 go through sth
▲knife through sth
The cruiser knifed through the heavy sea.巡洋舰穿过汹涌的大海。
A new highway knifes through the jungle.一条新公路穿越森林。

用作及物动词
▲S+～+n./pron.
The criminal knifed his victim in a rage.那个罪犯暴怒之下用刀砍了被害者。
The thief knifed his chaser.那窃贼用刀刺追赶他的人。
A terrible pain knifed his body.一阵剧痛像刀割似地穿过他的身体。
◇ 用于be ～ed结构
The victim has been knifed.受害人受到刀伤。
During the fight he was knifed in the stomach.在战斗中他的腹部挨了一刀。

knife用作名词时的复数为knives,而用作动词时的单数第三人称则须用knifes。

［词源］  ＜古英语cnif(刀)

1.knife是刀的总称,指用来切东西的工具,通常是有柄的,可指用来吃饭的餐刀,也可指菜刀,还可用来指武器。
2.knife的复数形式为knives。

have〔get〕 one's knife in〔into〕 sb
跟某人过不去,敌视某人 continue to treat sb as an enemy
Be careful with George; he wants to get his knife in you.你得提防乔治,他想报复你。
She has had her knife into the neighbours after the argument about the new fence.为新栅栏的事争论后,她对邻居有了敌意。

like a knife through butter
容易,遇不到抵抗或困难 easily; without meeting any resistance or difficulty
The power saw sliced the logs like a knife through butter.电锯轻而易举地就把原木锯成薄板了。
His strong voice cut through the hum of conversation like a knife through butter.他那洪亮有力的声音一下子就压倒了嗡嗡的谈话声。

you could cut it with a knife
很明显,很突出,浓重 it was very obvious or heavy
His accent is so thick you could cut it with a knife— I can hardly understand a word he says.他的口音很重——我简直一个字都听不懂。

He immersed the knife in boiling water.他把刀浸入沸腾的水中。
Blade and handle are the component parts of a knife.刀身和刀柄是一把刀的组成部分。
The knife is dull.那把小刀很钝。
Is this knife sharp or dull?这把刀快不快?
The knife is so dull that it will not cut.刀子太钝了,切不开东西。
He is awkward with a knife and fork.他吃东西用刀叉感到别扭。
Put your knife and fork down on the plate if you've finished eating.如果你已吃完饭,把刀叉放在盘子里。
He carved the meat with a large knife.他用一把大刀切肉。
He'd been stabbed four times with a kitchen knife.有人用厨刀捅了他四刀。
This is the identical knife with which the murder was committed.这就是凶手杀人时所用的刀子。
The jewel thief killed one of the policemen with a knife.珠宝贼用刀子杀死了一名警察。
He picked up the knife and stabbed her.他拿起刀,刺了她。
▲S+～+to-v
I need a knife to spread butter on the bread.我需要用一把刀在面包上涂黄油。