可數名詞與不可數名詞
在英文中，名詞是可數還是不可數，都會決定前面該用哪個限定詞，也會決定後面的動詞型態，因此務必要區分名詞是可數還是不可數。
可數名詞
可數名詞可以用數字來計算。這種名詞有單數和複數形；單數形的限定詞可以用 a 或 an。如果要詢問某個可數名詞的數量有多少，可以用「How many?」來問，再搭配可數名詞的複數形。
| 單數 | 複數 |
|---|---|
| one dog | two dogs |
| one horse | two horses |
| one man | two men |
| one idea | two ideas |
| one shop | two shops |
例句
- She has three dogs.
- I own a house.
- I would like two books please.
- How many friends do you have?
不可數名詞
不可數名詞無法用數字來計算。這類名詞可能是抽象的概念，或者太小、非固態的物體（液體、粉狀物、氣體等）。不可數名詞會使用動詞單數形，通常沒有複數形。
舉例
- tea
- sugar
- water
- air
- rice
- knowledge
- beauty
- anger
- fear
- love
- money
- research
- safety
- evidence
我們不能在不可數名詞前面加 a 或 an，如要表達它的數量，就得用 some、a lot of、much、a bit of、a great deal of 之類的量詞來表達，要更確切的話還可以用 a cup of、a bag of、1kg of、1L of、a handful of、a pinch of、an hour of、a day of 等量詞或測量單位。如果想詢問數量，可以用「How much...?」來問。
例句
- There has been a lot of research into the causes of this disease.
- He gave me a great deal of advice before my interview.
- Can you give me some information about uncountable nouns?
- He did not have much sugar left.
- Measure 1 cup of water, 300g of flour, and 1 teaspoon of salt.
- How much rice do you want?
微妙之處
有些名詞在別的語言中可數，但在英語中卻不可數，因此得遵循不可數名詞的規則。這類名詞最常見的有：
accommodation, advice, baggage, behavior, bread, furniture, information, luggage, news, progress, traffic, travel, trouble, weather, work
例句
- I would like to give you some advice.
- How much bread should I bring?
- I didn't make much progress today.
- This looks like a lot of trouble to me.
- We did an hour of work yesterday.
要特別留意的是 hair 這個名詞，在英語中一般是不可數的，因此通常不會用複數形，只有在特指單根頭髮時才會是可數名詞。
例句
- She has long blond hair.
- The child's hair was curly.
- I washed my hair yesterday.
- My father is getting a few grey hairs now.（指的是一根根的頭髮）
- I found a hair in my soup!（指的是單根的頭髮）