Indefinite Articles

2.1.1 The Indefinite Article ‘a/an’:

The form a is used before a word beginning with a consonant, or a vowel with a consonant sound. 

Examples: a man         a European               a university

                  a hat          a one-way street       a ewe

The form an is used before words beginning with a vowel (a, e, I, o, u) or words beginning with a mute consonant, or before individual letters spoken with a vowel sound.

Examples: an apple       an island                     an M.P

                  an yield        an  egg                      an hour

Use of ‘a/an’:

1.a/an is used before a singular noun which is countable, when it is mentioned for the first time and represents no particular person or thing.

 Examples: I need a pen.

                  They live in a bungalow.

2.a/an is used before a singular countable noun which is used as an example of a class of things.

 Examples: A child needs love. (all children, any child)

                   A car must be maintained. (all cars, any car)

3. a/an is used in certain expressions of quantity, with certain numbers and in expressions of price.

 Examples: a lot of                 a couple          Rs.10 a kilo

                  a great many        a dozen           50ps a dozen

 Before half when half follows a whole number. However, a half holiday, a half portion, a half share is possible.

 Examples: 1 ½ kilos=one and a half kilos or a kilo and half, but 1/2kg=half a kilo (not a before half)

4.In exclamations before singular, countable nouns.

 Examples: Such a long queue!

                  What a pretty girl!

5.a can be placed before Mr./Mrs./Miss.

Examples: A Mr. Patel, means a man called Patel and implies that he is a stranger to   the speaker.

               Mr. Patel, would mean that the speaker knows him.

6.a/an are used in the following cases.

 Examples: in an assembly of 30 people            a breach of peace

                  to give an assurance                        lack of a quorum

 Note:

 The indefinite article cannot be used before plurals So,

  a man – men (not a men)

  an ostrich – ostriches (not an ostriches)