difficulty n.困难,艰难,难事；有可数名词和不可数名词两种用法。 ①用作不可数名词，意为"困难、艰难",常用在以下句型中 have no/find(some,any,much) difficulty with sth./(in) doing sth. There is no (some,any,much) difficulty (in) doing sth. I had no difficulty in learning English. There was much difficulty (in) explaining it to him. ②用作可数名词。表示具体的困难，意为"难事,难点,困境,难处" This book is full of difficulties. In face of so many difficulties,we never appeared to be afraid.
difficulty有复数形式
difficulty n.困难,艰难,难事；有可数名词和不可数名词两种用法
①用作不可数名词,意为"困难、艰难",常用在以下句型中
have no/find(some,any,much) difficulty with sth./(in) doing sth.
There is no (some,any,much) difficulty (in) doing sth.
I had no difficulty in learning English.
There was much difficulty (in) explaining it to him.
②用作可数名词,表示具体的困难,意为"难事,难点,困境,难处".
This book is full of difficulties.
In face of so many difficulties,we never appeared to be afraid.
用单数或者用复数都可以，含义稍有区别。“have some difficulty” 表示“有某种困难”,“have some difficulties ”表示“有一些困难”，意思有差别。
例句：
have some difficulty
1、I have some difficulty which is beyond my expectations and my reach.
我遇到了一些困难，这些是在我意料之外的也是我能力范围之外的。
2、I have some difficulty with my study and I don't know how to talk to my new classmates.
我学业上有点困难而且我不知道如何和我的新同学交谈。
3、I have some difficulty understanding him.
我理解他有些困难。
4、I have some difficulty ( in) answering the question.
回答这个问题我有点困难。
have some difficulties
1、Thanks. I still have some difficulties, however.
谢谢.但是我仍然有些困难。
2、Unfortunately this is a breed which can have some difficulties with health.
可惜这是一个品种能有健康的一些困难。
3、In case I have some difficulties, please give me some explanations.
万一我遇到难题，请给我解释一下。
4、When you have some difficulties in life, the friends will undertake them with you, thisis friendship.
当您生活有啥困难时，好朋友们也会与您一起度过，这是友谊。
difficulty n.困难,艰难,难事；有可数名词和不可数名词两种用法。
①用作不可数名词，意为"困难、艰难",常用在以下句型中
have no/find(some,any,much) difficulty with sth./(in) doing sth.
There is no (some,any,much) difficulty (in) doing sth.
I had no difficulty in learning English.
There was much difficulty (in) explaining it to him.
②用作可数名词。表示具体的困难，意为"难事,难点,困境,难处"
This book is full of difficulties.
In face of so many difficulties,we never appeared to be afraid.
difficulty有复数形式
difficulty n.困难,艰难,难事；有可数名词和不可数名词两种用法
①用作不可数名词,意为"困难、艰难",常用在以下句型中
have no/find(some,any,much) difficulty with sth./(in) doing sth.
There is no (some,any,much) difficulty (in) doing sth.
I had no difficulty in learning English.
There was much difficulty (in) explaining it to him.
②用作可数名词,表示具体的困难,意为"难事,难点,困境,难处".
This book is full of difficulties.
In face of so many difficulties,we never appeared to be afraid.
是单数形式。
复数形式为：
transitional academic difficulties
注意：difficulty意思是困难之处。
你好~
可以是单数也可以是复数
policy的名词复数是policies
difficulty的名词复数是difficulties
附：
抽象名词的数
抽象名词大多是不可数的，不能计数，因而没有单、复数之分。例如：
Honesty is the best policy.
Knowledge is strength.
但也有一些抽象名词是可数的，如victory, a victory, two victories; conference, a conference, several conferences。还有一些抽象名词可以复数形式出现，但不能计数。例如difficulty, difficulties; opinion, opinions。
还有一些抽象名词有复数与非复数两种形式，但表示不同的意义。以experience一词为例：当experience作“经验”解时，它没有复数，但作“经历”解时，两种形式均可。例如：
The salesman met once a week to exchange experience（经验）。
Please tell us about your experiences（经历）in Africa.
有些抽象名词表示抽象概念是不可数名词，而表示具体事物则是可数名词。例如relation作“关系”解是不可数名词，而作“亲戚”解则是可数名词；Youth作“青春”、“青年”（集合体）解是不可数名词，而作“男青年”解则是可数名词；worry作“忧愁”、“烦恼”解是不可数名词，而作“烦恼事”解则是可数名词。
有些抽象名词本身没有复数形式，如果要计数，就得用在语义上与之对应的个体名词。例如：
抽象名词 个体名词
laughter laugh
work job
correspondence（通信）letter, note, ect.
photography photo
permission permit
music song
fun joy
homework exercise
英语中还有少数几个名词，如family, room, mouth, ear,等，似乎只能是可数名词，但实际上这类名词在某些搭配中也可表示抽象概念，从而成为不可数名词，例如to have too much family (=too heavy family burden), to have too much winter (= a too long spell of cold weather); to have too much mouth (= to talk too much), to have too little ear (= to be not inclined to listen to others), to have room for (=to have a need for), to feel the patriot rise... (=to feel the patriotic feelings rise...)等。
英语中还有一些名词（大多是指人的名词），通常作可数名词，但在特殊的搭配中表示人的特质等抽象意义时便成了不可数名词。例如fool本属可数名词，但在to be fool enough (=to be foolish enough), more of a fool (=more foolish), as much of a fool as (=as foolish as), too much of a fool (too foolish) 等搭配中，便表示抽象意义，成为不可数名词。类似的名词还有man,coward, poet, politician, sportsman, scholar 等。例如：
He was enough of a man to tell the truth.
上述这类现象只限于少数名词用在特殊的搭配中。
希望对你有帮助
population的基本意思是“人口”,还可指居住在某地的“全体居民”,作主语时谓语动词用单数形式; 在表示人口“多”“少”时,用large和small修饰。特指某一地区或某一国家的“人口”时,则前常加冠词the。
population用作可数名词,表示一个地区的“特定人群”“动物群”时,其前常加定冠词the。
population是集合名词,有时可加不定冠词,有时可用复数形式。
population
英 [?p?pju?le??n] 美 [?pɑ:pju?le??n]
n.人口;全体居民;特定[生物]种群;[物]布居。
例句：
Rice is the staple food of more than half the world's population
稻米是全世界一半以上人口的主食。
扩展资料：
population的近义词：
1、citizenry
英 [?s?t?z?nri] 美 [?s?t?z?nri]
n.公民成市民（集合称）。
I think we lack a citizenry that is adequately willing to take responsibility.
我觉得我们缺乏非常愿意承担责任的公民。
2、people
英 [?pi:pl] 美 [?pip?l]
n.人民;人，人类;居民;种族
vt.居住于，布满;使住满人，在…殖民;把动物放养在。
Millions of people have lost their homes.
数百万人流离失所。