We use 'a' before a consonant and 'an' before a vowel.
Examples:
a dog
a cat
a ticket
but:
an umbrella
an orange
an an honest man
attention! as it depends on the pronunciation of the following word, not the spelling.
an S.O.S.
an hour
We use 'one', not a/an:
- In contrast with another or other(s)
- In the expression one day
- With hundred and thousand when we want to sound precise
- In expressions like only one and just on
Examples:
One girl wanted to go out, but the others wanted to stay at home.
One day I'll take you to meet my family.
'How many are there? About a hundred?' 'Exactly one hundred and three.'
We've got plenty sausages, but only one egg.
Hope you've enjoyed this lesson! englishlessons