2 Use of a/an
a/an is used:
A Before a singular noun which is countable (i.e. of which there is more than one) when it is mentioned for the first time and represents no particular person or thing:
I need a visa. They live in a flat. He bought an ice-cream.
B Before a singular countable noun which is used as an example of a class of things:
A car must be insured
All cars/Any car must be insured.
A child needs love
All children need/Any child needs love.
C With a noun complement. This includes names of professions:
It was an earthquake. She’ll be a dancer. He is an actor.
D In certain expressions of quantity:
a lot of a couple
a great many a dozen (but one dozen is also possible)
a great deal of
E With certain numbers:
a hundred a thousand (See 349.)
Before half when half follows a whole number;
1 ½ kilos = one and a half kilos or a kilo and a half
But ½ kg = half a kilo (no a before half), though a + half + noun is sometimes possible:
a half-holiday a half-portion a half-share
With 1/3, ¼, 1/5 etc. a is usual: a third, a quarter etc., but one is also possible. (See 350.)
F In expressions of price, speed, ratio, etc.:
5p a kilo £1 a metre sixty kilometres an hour
10 p a dozen four times a day
(Here a/an = per)
G In exclamations before singular, countable nouns:
Such a long queue! What a pretty girl! But
Such long queues! What pretty girls!
(Plural nouns, so no article. See 3.)
H a can be placed before Mr/Mrs/Miss + surname:
a Mr Smith a Mrs Smith a Miss Smith a Mr Smith
means 'a man called Smith' and implies that he is a stranger to the speaker. Mr Smith, without a, implies that the speaker knows Mr Smith or knows of his existence.
P.Misheel
