staff可数集合名词第一类  形式为单数,但意义可以用为单数或复数这类集合名词包括family(家庭Y:'Times  New  Roman' >family(,team(队),class(班),audience(听众)等,其用法特点为：若视为整体,表示单数意义；若考虑其个体成员,表示复数意义.比较并体会：His  family  is  large.他的家是个大家庭.His  family  are  all  waiting  for  him.他的一家人都在等他.This  class  consists  of  45  pupils.这个班由45个学生组成.This  class  are  reading  English  now.这个班的学生在读英语. 这个班的学生在读英语.第二类  形式为单数,但意义永远为复数这类集合名词包括cattle(牛,牲畜)cattle(,people(人),police(警察)等,其用法特点为：只有单数形式,但却表示复数意义,用作主语时谓语用复数；不与  a(n)  连用,但可与the连用(连用).如：People  will  laugh  at  you.人们会笑你的.The  police  are  looking  for  him.警察在找他.Many  cattle  were  killed  for  this.就因为这个原因宰了不少牲畜.注：表示牲畜的头数,用单位词  head(单复数同形).如：five  head  of  cattle  5头牛,fifty  (head  of  )  cattle  50头牛  第三类  形式为复数,意义也为复数这类集合名词包括goods(货物),clothes(衣服)等,其用法特点是：只有复数形式()当然也表示复数意义,用作主语时谓语也用复数),但通常不与数词连用.如：Clothes  dry  slowly  in  the  rainy  season.衣服在雨季不易干.Such  clothes  are  very  expensive.那样的衣服很贵.If  goods  are  not  well  made  you  should  complain  to  the  manufacturer.如果货物质量不好,则理应向制造商提出控诉.第四类  形式为单数,意义也为单数这类集合名词包括baggage  /  luggage(行李),clothing(衣服),furniture(家具),machinery(机器),poetry(诗),scenery(风景),scenery(),jewelry(珠宝),equipment(设备)等,其用法特点为：是不可数名词,只用单数形式,不用不定冠词(当然更不能用数词),没有复数形式.如：Our  clothing  protects  us  from  [against]  the  cold.我们的衣服可以御寒.Have  you  checked  all  your  baggage?你所有的行李都托运了吗?The  thief  stole  all  her  jewelry.小偷把她所有的首饰都偷走了.The  hospital  has  no  decent  equipment.这家医院没有像样的设备.The  Tang  Dynasty  is  thought  of  as  the  high  summer  of  Chinese  poetry.人们认为唐朝是中国诗歌的全盛时期.注：machinery,poetry,jewelry,scenery等相应的个体可数名词是  machine,poem,jewel,scene等.如：a  poem  /  a  piece  of  poetry  一首诗many  machines  /  much  machinery  /  many  pieces  of  machinery  许多机器  第五类  1.hair(头发,毛发)  指全部头发或毛发时,为集合名词(不可数)；指几根头发或毛发时,为个体名词(可数).如：My  hair  has  grown  very  long.我的头发已长得很长了.The  police  found  two  hairs  there.警察在那儿找到了两根头发. 2.mankind(人类)  人是一个不可数的集合名词,不用复数形式,也不连用冠词.如：This  is  an  invention  that  benefits  mankind.这是一项造福人类的发明.Mankind  has  its  own  problems.人类有自己的问题.注：mankind  表示“mankind  人(类)”时,虽不可数,但有时却可以表示复数意义,尤其是当其表语是复数时.如：Mankind  are  intelligent  animals.人是理智的动物. 3.fruit(水果)  作为集合名词,它通常是不可数的.如：He  doesn’t  eat  much  fruit.他不大吃水果.He  is  growing  fruit  in  the  country.他在乡下种水果.但是,当要表示种类时,它可视为可数名词,即a  fruit  指一种水果,fruits  指多种水果.比较：fruits  Some  fruits  have  thick  skins.有些水果皮很厚.
staff是可数名词还是不可数名词