s后面加什么字母

一般情况，直接加-s，如book-books, bag-bags, cat-cats, bed-beds。

以s、x、sh、ch结尾，加-es，如bus-buses, box-boxes, brush-brushes, watch-watches。

以“辅音字母+y”结尾，变y为i，再加-es，如family-families, strawberry-strawberries。

以“f或fe”结尾，变f或fe为v，再加-es，如knife-knives。

不规则名词复数

man-men, woman-women, policeman-policemen, policewoman-policewomen, mouse-mice，child-children, foot-feet, tooth-teeth, fish-fish, people-people, Chinese-Chinese, Japanese-Japanese

不可数名词的复数就是原型 paper, juice, water, milk, rice, tea。