A noun like house, engineer, girl, name refers to a whole class of people or things. We use a/an with a noun to talk about just one member of that class. (A/an means 'one'.)
She lives in a nice big house. My father is an engineer. (NOT My father is engineer.) A girl phoned this morning. Tanaka is a Japanese name.
We use a/an when we define or describe people or things (when we say what class or kind they belong to).
He's a doctor. She s a beautiful woman. 'What's that?' 'It's a calculator. '
We do not use a/an with a plural or uncountable noun (see 92), because a/an means 'one'.
My parents are doctors (NOT . . . a doctors.) Would you like some salt?(NOT . . . a salt.)
We do not use a/an with an adjective alone (without a noun). Compare:
She's a very good engineer. She's a very good.(NOT She's a very good.)
We do not use a/an together with another determiner (for example my,your).
He s a friend of mine. (NOT He's a my friend.)
Note that we write another in one word.
Would you like another drink? (NOT . . . an other drink?)
Fact
An apple, onion, and potato all have the same taste. The differences in flavor are caused by their smell. To prove this you can pinch your nose and take a bite from each. They will all taste sweet. .. More >>