.什么是无标记复数名词？只要该名词一出现即为复数含义的名词就是无标记复数名词,其谓语动词用复数。如people,police,cattle,poultry,高中阶段一共就上述4个。可以和除了a或one以外的表示复数的数词连用。
a person \ two persons\ ten persons
two people\ ten people
a policeman\a policewoman
two policemen\ two policewomen
two police\ ten police
a head of cattle一头牛
ten heads of cattle十头牛
two cattle\ ten cattle两头\十头牛
a group of 36 cattle36头牛
twenty head of cattle = twenty cows=twenty cattle
two poultry\ ten poultry两只家禽\十只家禽
This vehicle is licensed to carry 4 persons.
此车准乘4人。
We were the only people there.
我们是唯一在场的人。
《牛津高阶英汉双解词典》
There's room for three people in the back.
后排有可容三人的空位。
There's only room for one person.
只有一个人的空间。
At least ten people were killed in the crash.
至少有十人在撞车事故中丧生。
另外，people 作为普通名词时“民族”解，是可以说;
a people一个民族
two peoples两个民族
the native peoples of Central and South America...
中南美洲的土著民族
These cattle are one of the purest breeds in Britain.
这些牛是英国最纯的品种之一。
The cattle were put out to pasture.
牛群放牧在牧场草地上。
The cattle were swinging their tails to disperse the flies.
那些牛甩动着尾巴驱赶苍蝇。
Cattle feed chiefly on grass.
牛主要以草为食。
On big farms cattle are usually stamped with brands.
在大农场，牲畜通常是打烙印的。
Some cattle were drinking at the pool.
有几头牛在那池塘边饮水。
After a summer here the poorest sheep and cattle grow strong and fat.
经过一个夏天，连最差的牛羊在这里也长得又肥又壮了。
The cattle are being fattened for slaughter
喂肥牛群以宰杀。
Poultry表示“家禽”为无标记复数名词：
The poultry are being fed.
家禽正在吃食。
Our poultry are kept at the bottom of the garden.我们的家禽养在花园的尽头。
Poultry作“禽肉”时为不可数名词：
Eat plenty of fish and poultry.
要多吃鱼和禽肉。
There is not much poultry in the shops.
商店里禽肉不太多。
2. 单复数同形名词好理解了，就是单词是可数名词，且单数和复数同形。如：sheep,deer,Japanese,Chinese和fish,下面通过经典例句意义说明它们的用法：
最简单的就是sheep,deer,很单纯，单复数同形，在中的单复数根据实际和句意来判断：
The sheep are allowed to roam freely on this land.
绵羊可以在这片地上自由走动。
They kept a small flock of sheep
他们养了一小群羊。
The sheep were turned out to graze.
羊被放出去吃草。
A sheep has wandered away from the flock.
一只羊走失了。
They killed a sheep as a sacrifice.
他们宰了一只羊作为祭品。
a herd of deer
一群鹿
He stalks his victims like a hunter after a deer.
他像猎手跟踪鹿一样悄悄跟踪受害人。
The lion arched its back to jump on the deer.
狮子拱起后背向鹿扑去。
The deer fell a prey to the lion.
鹿被狮子捕食了。
Huntsmen chased the deer silently.
猎人们悄悄地追捕那头鹿。
The deer clustered together near the water.
那些鹿集结在水边。
In the zoo,there are many deer.
动物园里有许多鹿。
The deer never became tame; they would run away if you approached them.
那些鹿一直没有被驯服：你一靠近，它们就跑开。
Japanese,Chinese既可以是单复数同形的名词，有时形容词，可说：
a Japanese一个日本人
a Chinese一个中国人
The Japanese are our biggest economic rivals.
日本人是我们最大的经济竞争对手。
The Japanese are expert at lowering manufacturing costs
日本人在降低制造成本方面很在行。
The chef, staff and managers are all Chinese.
厨师、工作人员和经理都是中国人。
The Chinese also eat a type of pasta as part of their staple diet
中国人也把一种面食作为他们的主食之一。
I’m a Chinese.我是一个中国人。
I’m Chinese.我是中国人。
I am Chinese and I am from Shanghai. 我是中国人，是从上海来的。
I am not English. I am Chinese. 我不是英国人。我是中国人。
关于fish用法
fish 鱼肉；是“不可数名词”；
He likes to eat fish. 他喜欢吃鱼肉。
There is much fish on the plate.盘子里有不少鱼肉。
fish 鱼，指鱼的条数，单数和复数相同；（国外母语知名学者认为此时的复数形式也可以是fishes， 所以此时fish的复数形式通常用 fish,也可用 fishes。）
They caught several fish.
他们捉到了几条鱼。
These fish are found in shallow waters around the coast.
这些鱼生长在海边浅水水域。
How many fish did you catch?
你捕到几条鱼？《牛津高阶英汉双解词典》
We caught three little fish.我们捉到三条小鱼。
These fish are often eaten raw.
这些鱼常常生吃。
当fish表示各种种类的鱼时复数为fishes，fishes可用于表示不同种类的鱼：
The list of endangered species includes nearly 600 fishes.
濒临灭绝物种的名单中列有将近600种鱼。