下列词加es:
1) s/x/ch/sh结尾的词加es
如:class, box, watch, brush, fox, match, dish, glass,
2)“辅音+y”结尾的词,y改为i后,加es
如:city, country, study,
3)下列o结尾的词加es: tomato,potato,hero,zero,mango,negro,...