规则1：在名词后加-s
例子：books, maps, cups, bags, teeth, cats, mice, days, hands, etc.
规则2：以s, x, ch, sh结尾的名词加-es
例子：boxes, glasses, watches, dishes, etc.
规则3：以辅音字母+y结尾的名词，变y为i，再加-es
例子：countries, babies, families, etc.
规则4：以f或fe结尾的名词，变f或fe为v，再加-es
例子：knives, leaves, wives, etc.
规则5：不规则变化
例子：ox→oxen, child→children, man→men, woman→women, foot→feet, tooth→teeth, mouse→mice, goose→geese, etc.
例外：
有些名词的单复数形式相同，如：sheep, deer, fish, means, etc.
有些名词的复数形式是在词尾加-th，如：truth→truths, breath→breaths, etc.
有些名词的复数形式是在词尾加-s-，如：compass→compasses, basis→bases, etc.
练习题：
1. 将下列名词变为复数形式：
– book
– map
– tooth
– mouse
– ox
– sheep
– child
– man
– woman
– leaf
2. 判断下列每组词中，哪一个是复数形式：
– [knife, knives]
– [ox, oxen]
– [man, men]
– [deer, deers]
– [sheep, sheeps]
3. 根据规律，写出下列名词的复数形式：
– box _______
– class _______
– watch _______
– toothache _______
– leaf _______
4. 根据所给中文提示，完成下列句子：
– There are two _______ () in Asia.
– How many _______ (手) do you have?
– These are my _______ (照片).
– I can see some _______ (鸭子) in the pond.