英语名词为什么会分可数与不可数？
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In my last post I talked about why it is important to know whether words in English are countable or uncountable. However, I didn't mention the fact that many words can be both countable and uncountable. This post discusses some of the reasons for this.
之前探讨了如何识别名词的可数与否（英语中名词的可数与否到底如何辨别？），今天继续探讨某些名词既可用作可数、也可用作不可数的原因是什么。
1）Food and drink is an area where words are commonly countable or uncountable. Often, the substance is uncountable, but a single portion (especially in the context of ordering something in a café) is countable（表食物和饮料类的名词，大多是既可用作可数又可用作不可数：当表示物质本身时，一般用作不可数名词；当 表示一份一份的食物或饮料时，一般用作可数名词）:
This café serves excellent coffee. (表“咖啡”物质，所以不可数)
They ordered three coffees. (表消费的“咖啡”份数，所以可数)
2）In addition, we often make foods countable when we talk about particular types of them（当表示不同类别的食物时，这些名词也是可数的）:
I don't like too much cheese on my pizzas. (表“奶酪”物质，所以不可数)
They make a wide range of blue cheeses. (表“奶酪”种类，所以可数)
3）In fact, we make this distinction between many other uncountable substances and countable types of those substances（英语中有更多这类名词，如wood，表示物质时是不可数的，但 表种类是是可数的）:
All the furniture is made from real wood. (表“树木”物质，所以不可数)
The woods they use are oak and mahogany. (表“树木”种类，所以可数)
4）In a similar way, we sometimes use uncountable nouns to talk about processes, situations, conditions etc. and countable nouns to talk about specific instances of them（有些名词，当我们笼统地表达其过程、形势和条件等时是不可数的，但当我们表达这些名词的具体内容时是可数的，如thought、disease等）:
The decision will require a lot of thought. (表“思考”的过程，所以不可数)
What are your thoughts on Max's suggestion? (表具体的“想法”，所以可数)
We are worried about the spread of disease. (表“疾病”的统称，所以不可数)
These diseases are spread by poor hygiene. (表具体的“疾病”，所以可数)
5）For some words, countability is an indicator of a completely different meaning（有些名词，可数与否的意思完全不一样，如definition）:
This dictionary has simplified definitions. (表“单词的含义”，是可数的)
The definition on these photos is very good. (表照片要表达的“主旨”，是不可数的)
6）For other words, countability can indicate a different but related meaning（有些名词，可数与否意思不同，但这些意思之间都是相关联的，如dress、land）:
She was wearing a long dress. (可数，表具体的一件衣服：裙子)
Formal dress is expected at the event. (不可数，表穿着，与裙子一样都是与衣服相关的)
They bought some land near their home. (不可数，表土地)
We travelled to a faraway land. (可数，表国家，多为文学用语)
7）On a more advanced note, we sometimes see differences in countability in specialised contexts. For example, the word 'behaviour' is typically uncountable, but it may be used as a countable noun in contexts such as psychology（同一个名词，适用场合不同，会存在可数不可数的差别）:
Their behaviour is usually good. (用来表示笼统的行为，不可数)
These children often exhibit disturbing behaviours. (用来表示具体的行为，可数)
8）And finally, another rather advanced point: pretty much any classically uncountable noun (which will be marked U only in a dictionary) can be made countable if you add an adjective before it. This use usually sounds rather literary（不可数名词如果被形容词修饰，往往可以用作可数名词，这种情况大多出现在文学用语中，如calm、hunger等）:
An uneasy calm descended on the room. （房间里笼罩着一种不安的平静气氛。）
We were tormented by a gnawing hunger. （我们遭受着饥饿的折磨。）
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