keys
1、名词由单数变复数的基本方法如下：
①在单数名词词尾加s.如：map → maps,boy→ boys,horse→ horses,table→ tables.
②s,o,x ,sh,ch结尾的词加es.如：class→classes,box→boxes,hero→heroes,dish→dishes,bench→benches.
[注]：少数以o结尾的词,变复数时只加s.如：photo→photos,piano→pianos.
③以辅音字母加y结尾的名词,变y为i,再加es.如：family→families,city→cities,party→parties.
④以f或fe结尾的名词,变f或fe为v,再加es.如：shelf→shelves,wolf→wolves,life→lives,knife→knives.
2、不规则变化：man→men,woman→women,sheep→sheep,tooth→teeth,fish→fish,child→children,ox→oxen,goose→geese
不可数名词一般没有复数形式,说明其数量时,要用有关计量名词.如：a bag of rice→two bags of rice,a piece of paper→three pieces of paper,a bottle of milk→five bottles of milk.