a

a — determiner

1. you place this word before a noun that labels one individual or object, when you

1.限定詞A1
釋義

you place this word before a noun that labels one individual or object, when your listener is encountering that item for the very first time

例句

Ananya bought a bicycle yesterday, but she has not ridden it yet.

first mention of bicycle

There is a small café on the corner of Park Street.

同義詞
  • some

    used in the same position for plural or uncountable nouns, e.g. 'some books' vs 'a book'

反義詞
  • the

    used when the listener already knows which one is meant

文法句型

a + singular countable noun

用法筆記

Use 'a' for the first mention of a countable noun. Once the listener knows which item you mean, switch to 'the' for later mentions.

常見錯誤

❌I saw a moon last night.
✅I saw the moon last night.
💡There is only one moon, so use 'the'.
❌She is a teacher and a teacher helped me.
✅She is a teacher and the teacher helped me.
💡After first mention, use 'the'.

2. this word comes after verbs like 'be' or 'become' to say which group an individu

2.限定詞A1
釋義

this word comes after verbs like 'be' or 'become' to say which group an individual or object fits into — for instance, what kind of animal, item, or human something is

例句

An octopus is a sea animal with eight long arms.

class membership statement

The Watanabe family owns a small restaurant near the station.

同義詞
  • one of

    emphasises membership in a larger group, e.g. 'one of the teachers'

文法句型

be + a + noun

become + a + noun

用法筆記

The structure 'subject + be + a + noun' is one of the most basic patterns in English. The noun tells the category; an adjective can be added before it.

常見錯誤

❌She is teacher.
✅She is a teacher.
💡Singular countable nouns used as complements need 'a' or 'an'.
❌He is a doctor and a nurse.
✅He is a doctor and a nurse too.
💡OK if he has both jobs, but each role needs its own article.

3. you place it in front of the name of someone's job or position when telling a li

3.限定詞A1
釋義

you place it in front of the name of someone's job or position when telling a listener what work that person does

例句

Elena works as a dentist at the city hospital.

job role: a + profession

Yuki's father is a police officer in Kyoto.

文法句型

be + a + job title

用法筆記

Always use 'a' or 'an' before a singular job title. Never omit it (❌ 'She is doctor'). If the profession starts with a vowel sound, use 'an' instead: 'an architect', 'an engineer'.

常見錯誤

❌My mother is nurse.
✅My mother is a nurse.
💡Job titles need an article.
❌He is an university professor.
✅He is a university professor.
💡'University' starts with a consonant sound /juː/.

4. in statements of general truth, it precedes a noun that stands for every member

4.限定詞A1
釋義

in statements of general truth, it precedes a noun that stands for every member of that class — 'a cat is a mammal' means all cats are mammals

例句

A cheetah can run much faster than a horse.

generic statement about a species

A good dictionary is an essential tool for any language learner.

同義詞
  • any

    stronger emphasis on 'no matter which', e.g. 'Any dog needs exercise'

文法句型

a + singular noun + verb (general truth)

用法筆記

In formal or academic English, generics can also be expressed with a plural noun without an article ('Cheetahs run fast') or with 'the' ('The cheetah runs fast'). The 'a' form is common in everyday speech.

常見錯誤

❌A dog are loyal animals.
✅A dog is a loyal animal.' or 'Dogs are loyal animals.
💡The verb must agree with the singular noun.
❌A books are useful.
✅A book is useful.' or 'Books are useful.
💡'A' cannot be used with plural nouns.

5. this replaces the number 'one' when talking about a single object or person, esp

5.限定詞A2
釋義

this replaces the number 'one' when talking about a single object or person, especially in everyday conversation where the exact count is not the main focus

例句

Raj asked for a glass of water and the waiter brought him two.

a = one, contrasted with two

There is only a single piece of cake left on the plate.

同義詞
  • one

    stronger emphasis on the number; 'a' is softer and more common in everyday use

文法句型

a + noun (meaning one)

用法筆記

'A' is the usual word for 'one' in everyday speech. Use 'one' instead when you need to emphasise the exact number in contrast to other possibilities ('I want one ticket, not two').

常見錯誤

❌He only has a eye.
✅He only has one eye.
💡Use 'one' (not 'a') before a vowel sound when the number is important. But 'an eye' is correct for first mention.
❌I have a sister and a brother.
✅I have one sister and one brother.
💡When counting, 'one' is clearer.

6. it sits between two units of weight, time, money, or distance to tell you the ra

6.限定詞A2
釋義

it sits between two units of weight, time, money, or distance to tell you the rate: how much of something happens for each item or period

例句

The train to London runs every hour and costs forty pounds a ticket.

cost per unit: a ticket

Dewi jogs five kilometres a day in the park near her house.

frequency: a day

同義詞
  • per

    more formal, e.g. 'per hour', 'per person'

文法句型

number + unit + a + time/money unit

用法筆記

In this sense, 'a' and 'an' are interchangeable with 'per' but sound more natural in spoken English. 'Per' is more formal and common in writing. Use 'an' before vowel sounds: 'an hour', 'an acre'.

常見錯誤

❌I read two books a one week.
✅I read two books a week.
💡Do not add 'one' after 'a' in rate expressions.
❌The salary is £30,000 one year.
✅The salary is £30,000 a year.
💡Use 'a' not 'one' for rates.

7. it pairs with words that express a strong feeling — including 'what', 'such', 'q

7.限定詞A2
釋義

it pairs with words that express a strong feeling — including 'what', 'such', 'quite' and 'rather' — when a person reacts with wonder, joy, or irritation about something they observe

例句

What a beautiful sunset we saw from the top of the mountain!

what a + adjective + noun (exclamation)

Noam is such a talented pianist that the audience clapped for five full minutes.

such a + adjective + noun

文法句型

what + a + adjective + noun!

such + a + adjective + noun

quite + a + noun

用法筆記

The order of words after 'quite' and 'rather' can vary. Both 'quite a big project' and 'a quite big project' are acceptable, though 'quite a' is more common in British English.

常見錯誤

❌What beautiful sunset!
✅What a beautiful sunset!
💡'What' in exclamations needs 'a' before a singular countable noun.
❌She is such a honest person.
✅She is such an honest person.
💡'Honest' starts with a vowel sound.

8. you put it in front of a person's name — usually with a title like Mr. or Dr. —

8.限定詞B1
釋義

you put it in front of a person's name — usually with a title like Mr. or Dr. — to tell the listener that you are talking about someone neither of you knows personally

例句

A Mr. Tanaka called while you were out and left his number on the desk.

a + title + surname (unknown caller)

The receptionist said that a Dr. Williams was waiting in the lobby to see you.

同義詞

文法句型

a + title + surname

用法筆記

Use this pattern when you are introducing someone the listener does not know. If the listener already knows the person, omit 'a' ('Mr. Tanaka called'). This pattern is slightly formal.

常見錯誤

❌A John is here to see you.
✅A Mr. John Smith is here to see you.' or 'A man named John is here.
💡'A' before a first name alone sounds unnatural; add a title or description.
❌I spoke to a doctor Smith.
✅I spoke to a Dr. Smith.
💡The title should match the person's actual title.

9. normally you cannot put 'a' in front of uncountable nouns like 'knowledge' or 's

9.限定詞B1
釋義

normally you cannot put 'a' in front of uncountable nouns like 'knowledge' or 'silence', but when a describing word or a longer phrase comes between them, it becomes acceptable because you are talking about one special kind or degree

例句

The students showed a deep understanding of the topic after the workshop.

a + adjective + uncountable noun (understanding)

Elena gained a solid knowledge of Japanese after living in Tokyo for three years.

文法句型

a + adjective + uncountable noun

用法筆記

Normally uncountable nouns (like 'understanding', 'knowledge', 'silence', 'education') do not take 'a'. But when they are modified by an adjective or a 'of'-phrase, 'a' becomes acceptable to show a specific type or degree.

常見錯誤

❌I need an advice.
✅I need some advice.' or 'I need a piece of advice.
💡'Advice' is uncountable; combine with 'a' only when modified ('a good advice' is still wrong). ✅ 'He gave me a valuable piece of advice.'
❌We had a great weather.
✅We had great weather.' or 'We had a spell of great weather.
💡'Weather' is uncountable.

10. this word appears inside fixed expressions that tell you the amount of something

10.限定詞A2
釋義

this word appears inside fixed expressions that tell you the amount of something, such as 'a few', 'a little', 'a lot of', and 'a great deal of'

例句

Neha invited a few friends over for dinner on Saturday evening.

a few + plural noun (small number)

There is only a little milk left in the fridge, not enough for coffee.

a little + uncountable noun

同義詞
  • some

    can replace 'a few' or 'a little' in most contexts

反義詞
  • few

    without 'a' means 'not enough' or 'hardly any'

  • little

    without 'a' means 'not much'

文法句型

a few + plural noun

a little + uncountable noun

a lot of + noun

用法筆記

Be careful with 'few' vs 'a few', and 'little' vs 'a little'. 'A few / a little' means 'some' (positive). 'Few / little' without 'a' means 'not enough' (negative). Compare: 'I have a few friends' (some) vs 'I have few friends' (not enough).

常見錯誤

❌I have a few money.
✅I have a little money.
💡'Few' goes with plural countable nouns; 'little' goes with uncountable nouns.
❌She has a lot books.
✅She has a lot of books.' or 'She has lots of books.
💡'A lot of' needs the preposition 'of'.

11. after a negative word such as 'not', 'never', or 'without', this word sits in fr

11.限定詞B1
釋義

after a negative word such as 'not', 'never', or 'without', this word sits in front of a noun to stress that absolutely nothing of that thing exists

例句

The thief left the house without leaving a single fingerprint behind.

without + a + singular noun (zero quantity)

Dewi did not make a single mistake in the entire English exam.

同義詞
  • no

    more direct, e.g. 'He made no mistakes' — but 'no' works with both singular and plural

文法句型

not + a + singular noun

never + verb + a + singular noun

用法筆記

Adding 'single' after 'a' ('not a single...') makes the emphasis even stronger. This pattern is common after 'not', 'never', 'without', and 'hardly'.

常見錯誤

❌He did not make mistake.
✅He did not make a mistake.
💡Singular countable nouns in negative sentences still need 'a'.
❌There is not a any reason.
✅There is not a single reason.' or 'There is no reason.
💡Do not combine 'a' with 'any'.

12. you put it in front of everyday sicknesses like 'cold', 'headache', 'fever', or

12.限定詞A2
釋義

you put it in front of everyday sicknesses like 'cold', 'headache', 'fever', or 'cough' when telling someone you are feeling unwell or have caught something

例句

Fatima stayed home from school because she had a bad cold and a fever.

have + a + illness

Arjun went to the pharmacy to get some medicine for a headache.

文法句型

have + a + illness

catch + a + illness

get + a + illness

用法筆記

Not all illnesses take 'a'. More serious or scientific disease names often do not: 'cancer', 'diabetes', 'malaria' (no 'a'). The illnesses that take 'a' are generally common, everyday ones: 'a cold', 'a cough', 'a fever', 'a headache', 'a stomach ache'.

常見錯誤

❌I have a diabetes.
✅I have diabetes.
💡'Diabetes' is uncountable; do not use 'a'.
❌She has a flu.
✅She has the flu.' or 'She has flu.
💡'Flu' often takes 'the', not 'a'.

13. you say it in front of number-words including hundred, thousand, million, or doz

13.限定詞A2
釋義

you say it in front of number-words including hundred, thousand, million, or dozen to signal one of that quantity — used especially when giving round or approximate figures

例句

Ananya saved a hundred dollars by buying the flight tickets early.

a hundred = one hundred

Over a thousand people attended the music festival in the park last weekend.

同義詞
  • one

    more precise; 'a' is softer and more natural in everyday contexts

文法句型

a hundred/thousand/million/dozen + noun

用法筆記

'A' and 'one' are interchangeable before these numbers, but 'a' is more common in everyday speech. Use 'one' for precise or contrastive counting ('one hundred, not two hundred'). After the first word in a larger number, do not repeat 'a': 'a hundred and twenty-three', not 'a hundred and a twenty-three'.

常見錯誤

❌There were a hundreds of birds.
✅There were hundreds of birds.' or 'There were a hundred birds.
💡Use 'a hundred' before a noun, but 'hundreds of' without 'a' when generalising.
❌A thousand people came, a thousand and a fifty.
✅A thousand and fifty people came.
💡Do not repeat 'a' before 'fifty'.

14. normally uncountable nouns do not take 'a', but when you want to point out a spe

14.限定詞B1
釋義

normally uncountable nouns do not take 'a', but when you want to point out a specific variety, brand, or quality — such as a particular cheese or wine — it becomes correct

例句

The shop sells a very soft cheese that comes from a small farm in France.

a + adjective + cheese (specific variety)

Thomas ordered a red wine that the waiter recommended with the lamb dish.

同義詞
  • a kind of

    more explicit, e.g. 'a kind of soft cheese'

文法句型

a + uncountable noun (specific type)

用法筆記

This is a more advanced use where normally uncountable nouns (cheese, wine, kindness, beauty) are treated as countable to mean 'a type of' or 'a particular quality of'. Common with foods, materials, and abstract qualities.

常見錯誤

❌I would like a coffee please.
✅I would like coffee.' or 'I would like a cup of coffee.
💡However, in many cafes 'a coffee' (meaning a cup) is now accepted.
❌She has a great patience.
✅She has great patience.
💡'Patience' is abstract and uncountable; it rarely takes 'a' even with an adjective.

15. you put it in front of a name that has been given an adjective, to highlight a c

15.限定詞B1
釋義

you put it in front of a name that has been given an adjective, to highlight a certain period, version, or set of qualities — for example, a different or new version of a country or artist

例句

After the reforms, the country entered a new China that welcomed foreign investment.

a + adjective + place (new era)

The curator described the sculpture as a very different Picasso from his earlier works.

文法句型

a + adjective + proper noun

用法筆記

This pattern is common in journalism, literature, and descriptive writing. The adjective before the proper noun highlights specific qualities, periods, or interpretations of that person or place.

常見錯誤

❌He is a Shakespeare in writing.
✅He is a modern-day Shakespeare when it comes to writing.
💡The comparison needs to be clear; just 'a Shakespeare' can confuse listeners.
❌It was a beautiful Taipei.
✅A beautiful Taipei greeted us.
💡The sentence needs context that gives a sense of experiencing or discovering that version of the place.

a — noun

a — abbreviation