单复数相同 sheep, deer, means, works, fish, yuan 3 只有复数形式 trousers, clothes, thanks, goods, glasses, 4 一些集体名词总是用作复数 people, police 5 部分集体名词既可以作单数(整体)也可以作复数(成员) class, family, crowd, couple, group, government,...