where to use a

Uses of "A" Before a singular countable noun beginning with a consonant. Examples:- a dog , a B.A. , a nun Before the word "one" when "o" sounds as "wu" . Examples :- a one eyed deer, a one horned rhino Before a noun beginning with "u" or "e" or "ew" which sounds as "yoo" . Examples :- a university, a unit, a useful, a European