We can use these words at the beginning of a noun phrase (Lesson 45). We use a/ an for singular nouns (a plate/ an apple) and some/ any for plurals and mass nouns (some plates/ any fruit) (Lesson 56).
use an if the next word begins with a, e, i, o, u:
an aunt, an exam, an idea, an old man, an uncle
BUT if we say u as in you:
a university, a used car
Use a if the next word begins with any other letter:
a cousin, a test, a thought, a young man, a boat
BUT if h is silent:
an hour, an honest man
Use some in affirmative sentences:
He's got some news. (Lesson 5)
Use any in negative sentences:
I haven't got any news. (Lesson 5)
We normally use any in questions (BUT look at Lesson 9).
There is a man at the door.
But I don't know who he is.
She bought some oranges.
I don't know which oranges.
She didn't buy any apples.
A bottle of water, please.
NOT one bottle; (Lesson 59)
a few, a little, a lot of, a pair, a hundred, a thousand, a million
forty kilometres an hour (NOT the hour), eighty cents a pound
NOTICE: a/ an/ some/ any or the or nothing? (Lesson 54)
something/ anything = a thing
somewhere/ anywhere = a place
someone/ anyone/ somebody/ anybody = a person