（一）名词复数规则
1．一般情况下，直接加-s，如： book-books, bag-bags, cat-cats, bed-beds
2．以s. x. sh. ch结尾，加-es，如： bus-buses, box-boxes, brush-brushes, watch-watches
3． 以“辅音字母+y”结尾，变y为i, 再加-es，如： family-families, strawberry-strawberries
4． 以“f或fe”结尾，变f或fe为v, 再加-es，（但有一个特例：roof→roofs）。
如： knife-knives leaf-leaves wife-wives thief-thieves wolf-wolves
5． 以“o”结尾的单词，如果有生命，加-es；如果没有生命，加-s。
如：①有生命：potato-potatoes tomato-tomatoes mango-mangoes
hero-heroes Negro- Negroes
②没生命：radio-radios piano-pianos photo-photos zoo-zoos
6． 不规则名词的复数变化：
（二）完全不规则：
man-men woman-women policeman-policemen
policewoman-policewomen mouse-mice child-children
foot-feet tooth-teeth
（三）单数复数词形相同：
fish-fish sheep-sheep deer-deer people-people Chinese-Chinese Japanese-Japanese
小练习：写出下列各词的复数
I _________ him _________ this ___________ her ______
watch _______ child _______ photo ________ diary ______
day________ foot________ book_______ dress ________
tooth_______ sheep ______ box_______ strawberry _____
thief _______ yo-yo ______ peach______ sandwich ______
man______ woman_______ paper_______ juice___________
water________ milk________ rice__________ tea__________