1、以s，x，ch，sh，z结尾的单词后加es，例如，bus-buseswatch-watches

2、以辅音字母加y结尾的，把y 变i加es，例如，baby-babies，lady-ladies

3、部分以o结尾的单词后加es，例如，potato-potatoes，hero-heroes

4、一般以f和fe结尾的单词要把f，或fe变为ves，例如，wife-wives，knife-knives