复数形式：knives。

以f或fe 结尾的名词变复数时，有两种方法：：

1、加s，例如：belief-beliefs、roof-roofs、safe-safes、gulf-gulfs 。

2、去f，fe加ves，例如：half-halves、knife-knives、leaf-leaves、wolf-wolves、wife-wives、life-lives、thief-thieves。

例句：

1、I have three knives. 

“我有3把小刀。”

2、There were forks, knives, spoons, and chopsticks.

“他们是叉子，刀子，勺子和筷子。”

3、I'm pricked and probed by what feels like knives, not needles.

“我觉得这些针剂更像是刀子，它们在刺我、在戳我。”

4、The stories I could tell you. Time and time again, how your knives have pulled my ass out of the fire.

“我可以跟你讲很多这样故事，关于你们生产的刀是怎样一次又一次的救我于水火之中。”