在句子中怎么区分要加S和ES或是保持原形.如：I don't have any bananas ,but i have some peaches.这一句是有加S和ES.如：I don't have any coffee,but I have

名词变复数
一、首先区别是可数还是不可数名词.banana 和peach是可数名词所以有复数形式.coffee 和milk是不可数名词没有复数,所以保持原形.
.二、名词复数的规则变化
1) 一般的名词在词尾加-S
students,apples,bags,trees,books,brothers.
2) 以s、ss、z、x、sh、ch结尾的名词加-es
glasses,boxes,brushes,matches.
补充说明：以-ch结尾的名词并不一定都是加es变复数,像stomach就是加s,关键还是要看发音的
3) 以辅音字母加y结尾的名词,变y为i加es
cities,babies,enemies
4) 以f或fe结尾的名词,多数变f为v加es
wives,knives,lives,wolves,shelves,leaves,bookshelves.
但有些词只加s:roofs,proof s,chiefs.
5) 以o结尾的名词,有些加es
Negroes,heroes,tomatoes,potatoes（黑人英雄爱吃土豆和西红柿）,
其它加s:radios,zoos,pianos,photos,banboos,kangaroos,
Eskimos,Filipinos(其中最后两个单词是以o结尾的种族名词)
二、名词复数的不规则变化
1)改变内部的母音字母：
foot→ feet,goose→ geese,tooth→ teeth,mouse→ mice,man→ men,woman→ women,policeman→ policemen,postman→ postmen,mailman→ mailmen,spaceman→ spacemen,gentleman→ gentlemen,milkman→ milkmen,businessman→ businessmen ,fisherman→ fishermen,policewoman→ policewomen,businesswoman→ businesswomen
2)单复数同形：
sheep→ sheep,deer→ deer,Chinese→ Chinese,Japanese→ Japanese
3)有些外来语保留原来的复数形式
datum→ data,medium→ media,bacterium→ bacteria,curriculum→ curricula,criterion→ criteria,phenomenon→ phenomena
4）加字尾en或ren
ox→ oxen,child→ children
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