单数&复数
单数（singular）：单数就是“单一的”或“一个“的意思。在英语语法中，名词、代词和动词都有单数形式。例如，car就是一个单数名词，he就是一个单数代词，而climbs就是一个动词在一般现在时中的单数形式。
复数(plural)：复数义为“多于一个”。在英语的语法当中名词、代词、动词都有其复数形式。例如，cars是名词复数形式，they和we是代词复数形式，climb是动词的复数形式。
可数名词有单数和复数，复数要在名词的词尾配合适当的变形，如加-s或-es等。
可数名词复数的变化规律：
规则变化：
(1)一般在词尾加-s
map-maps desk-desks hand-hands dog-dogs bee-bees
teacher-teachers
(2)以s,x,ch,sh结尾加-es
class-classes bus-buses box-boxes watch-watches brush-brushes bush-bushes match-matches
(3)以辅音字母+y结尾的名词，变y 为i加-es；而以元音字母+y结尾的名词则加-s；以y结尾的专有名词直接加-s
family-families city-cities country-countries baby-babies lady-ladies
boy-boys donkey-donkeys key-keys monkey-monkeys
Henry-Henrys
(4)以o为结尾的名词
加-es 的名词有
Negro-Negroes hero-heroes potato-potatoes tomato-tomatoes veto-vetoes
加-s 的名词有
photo-photos radio-radios piano-pianos kilo-kilos
bamboo-bamboos solo-solos tobacco-tobaccos
加-s和-es均可的名词有
volcano-volcanos-volcanoes motto-mottos-mottoes
memento-mementos-mementoes manifesto-manifestos-manifestoes
（5）以f或fe结尾的名词
一般变f，fe为v，再加-es的名词有
calf-calves knife-knives life-lives self-selves shelf-shelves wife-wives half-halves leaf-leaves
Loaf-loaves sheaf-sheaves thief-thieves wolf-wolves
直接加-s的名词有
roof-roofs chief-chiefs brief-briefs gulf-gulfs
cliff-cliffs reef-reefs proof-proofs
以上两种均可的名词有
hoof-hooves-hoofs dwarf-dwarves-dwarfs
handkerchief-handkerchieves-handkerchiefs
不规则变化：
（1）变元音字母
man-men woman-women foot-feet tooth-teeth goose-geese
（2）变词尾
child-children ox-oxen penny-pence
（3）单复数同形
Fish deer sheep means Swiss Chinese Japanese Lebanese Portuguese Vietnamese
（4）复合名词
由man和woman构成的复合名词，两个词都要变复数
man teacher-men teachers woman doctor-women doctors
有中心词的复合名词将中心词变复数
passer-by-passers-by looker-on-lookers-on
mother-in-law-mothers-in-law
没有中心词的复合名词直接在词尾加-s
go-between--go-betweens grown-up--grown-ups
（5）有些名词形式上虽是单数，意义上为复数
People cattle staff police public
（6）以is结尾的外来词变is为es
crisis- crises analysis-analyses
basis-bases diagnosis-diagnoses thesis-theses
（7）有些外来词有特殊的变化方式
formula-formulas-formulae index-indexes-indices
appendix-appendixes-appendices
bacterium-bacteria medium-media phenomenon-phenomena
mouse-mice
复数(plural)：复数义为“多于一个”。在英语的语法当中名词、代词、动词都有其复数形式。例如，cars是名词复数形式，they和we是代词复数形式，climb是动词的复数形式。
可数名词有单数和复数，复数要在名词的词尾配合适当的变形，如加-s或-es等。
可数名词复数的变化规律：
规则变化：
(1)一般在词尾加-s
map-maps desk-desks hand-hands dog-dogs bee-bees
teacher-teachers
(2)以s,x,ch,sh结尾加-es
class-classes bus-buses box-boxes watch-watches brush-brushes bush-bushes match-matches
(3)以辅音字母+y结尾的名词，变y 为i加-es；而以元音字母+y结尾的名词则加-s；以y结尾的专有名词直接加-s
family-families city-cities country-countries baby-babies lady-ladies
boy-boys donkey-donkeys key-keys monkey-monkeys
Henry-Henrys
(4)以o为结尾的名词
加-es 的名词有
Negro-Negroes hero-heroes potato-potatoes tomato-tomatoes veto-vetoes
加-s 的名词有
photo-photos radio-radios piano-pianos kilo-kilos
bamboo-bamboos solo-solos tobacco-tobaccos
加-s和-es均可的名词有
volcano-volcanos-volcanoes motto-mottos-mottoes
memento-mementos-mementoes manifesto-manifestos-manifestoes
（5）以f或fe结尾的名词
一般变f，fe为v，再加-es的名词有
calf-calves knife-knives life-lives self-selves shelf-shelves wife-wives half-halves leaf-leaves
Loaf-loaves sheaf-sheaves thief-thieves wolf-wolves
直接加-s的名词有
roof-roofs chief-chiefs brief-briefs gulf-gulfs
cliff-cliffs reef-reefs proof-proofs
以上两种均可的名词有
hoof-hooves-hoofs dwarf-dwarves-dwarfs
handkerchief-handkerchieves-handkerchiefs
不规则变化：
（1）变元音字母
man-men woman-women foot-feet tooth-teeth goose-geese
（2）变词尾
child-children ox-oxen penny-pence
（3）单复数同形
Fish deer sheep means Swiss Chinese Japanese Lebanese Portuguese Vietnamese
（4）复合名词
由man和woman构成的复合名词，两个词都要变复数
man teacher-men teachers woman doctor-women doctors
有中心词的复合名词将中心词变复数
passer-by-passers-by looker-on-lookers-on
mother-in-law-mothers-in-law
没有中心词的复合名词直接在词尾加-s
go-between--go-betweens grown-up--grown-ups
（5）有些名词形式上虽是单数，意义上为复数
People cattle staff police public
（6）以is结尾的外来词变is为es
crisis- crises analysis-analyses
basis-bases diagnosis-diagnoses thesis-theses
（7）有些外来词有特殊的变化方式
formula-formulas-formulae index-indexes-indices
appendix-appendixes-appendices
bacterium-bacteria medium-media phenomenon-phenomena
mouse-mice
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