以f结尾的单词什么情况下是变为ves什么情况下是直接加s如leaf是变为leaves还是变为leafs

问题描述:

以f结尾的单词什么情况下是变为ves什么情况下是直接加s
如leaf是变为leaves还是变为leafs

leaf-leaves(树叶) scarf-scarves/scarfs(围巾) handkerchief-handkerchieves/handkerchiefs(手帕) knife-knives(刀子) thief-thieves(小偷) life-lives(生命) self-selves(自己,myself-ourselves)...