knife复数形式knives，knife是刀的意思，

它遵循可数名词复数变化规则：以f或fe 结尾的名词，先去f，fe，再加ves。half-halves、knife-knives、leaf-leaves、wolf-wolves、wife-wives、life-lives、thief-thieves。

另外有些单词以f或fe 结尾加s，例如：belief-beliefs、roof-roofs、safe-safes、gulf-gulfs。

knife的第三人称单数：knives，复数：knives，现在分词：knifing，过去式：knifed ，过去分词：knifed。

This knife is his.(改成复数) These knives are theirs .

Whose knife is this?(改成复数) whose knives are those?

Is this your knife 改为复数句子 Are these your knives?

Two knife racks hold her favourite knives. 两个刀架上存放着她最心爱的刀具。

These fruit knives are very good for stripping apple skins off. 这种水果刀削苹果皮很好用.