How to use one articles forms

a/an and one (adjective)

 Rule 1: When counting or measuring time, distance, weight etc. we can use either a/an or one for the singular:

$1=a/one pound                             $10000 = a/one million pounds

But not that in the rent is $ 100 a week the a before week is not replaceable by one.

In other types of statement a/an and one are not normally.

Interchangeable, because one+ noun normally means ‘one only/not more than one’ and a/an does not mean this:

• A shotgun is no good.
• One shotgun is no good.

Rule 2: Special uses of one:

(a)   One (adjective/pronoun) used with another/others:

One (boy) wanted to read, another/ others wanted to watch TV.

One day he wanted his lunch early, another day he wanted it late.

(b)  One can be used before day/week/month/year/summer/winter etc. or before the name of the day or month to denote a particular time when something happened:

One night there was a terrible storm.

One winter the snow fell early.

One day a telegram arrived.

(c)   One day can also be used to mean ‘at some future date’ :

One day you’ll be sorry you treated him so badly.

a/an and one (pronoun)

One is the pronoun equivalent of a/an:

Did you get a ticket? –Yes, I managed to get one.

The plural of one used in this way is some:

Did you get tickets? – Yes, I managed to get some.

Introduction to Omission article used to A and An

Rule 1: The form a/an is used before plural nouns:

a/an has no plural form. So the plural of a dog is dogs, and of an egg is eggs.

Rules 2: Before names of meals, except when these are preceded by an adjective:

• We have breakfast at eight. 
• He gore us a good breakfast.

The article is also used when it is a special meal given to celebrate something or in someone’s honor:

• I was invited to dinner (at their house, in the ordinary way) but 
• I was invited to a dinner given to welcome the new ambassador.

How to use A and An the indefinite Articles

Rule 1: Before a singular noun which is countable. 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.

Rule 2: Before a singular countable noun which is used as an example of a class of things:

• A car must be insured. 
• A child needs love.

Rule 3: With a noun complement. This includes names of professions:

• It was an earthquake. 
• She’ll be a dancer. 
• He is a an actor.

Rule 4: In certain expressions of quantity:

a  lot of                 a couple               a great 

 a dozen               a great deal of

Rule 5: In expressions of price, speed, ration etc:

5p a kilo              1 a meter            sixty kilometers an hour

10p a dozen       four times a day

Rule 6: In exclamations before singular, countable nouns:

• Such a long queue!           
• What a pretty girl!

Rule 7: 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 the speaker knows Mr smith or knows of his existence.

Rule 8: With certain number:

A hundred          a thousand        

Before half when half follows a whole number:

A half-holiday                   a half-portion                   a half- share