use of articules

a: indefinite article.
an: indefinite article, with vowels.
the: definite article 

rules

The first time you speak of something use "a or an", the next time you repeat that object use "the".
    I live in a house. The house is quite old and has two bedrooms.
DO NOT use an article with countries, states, counties or provinces, lakes and mountains except when the country is a collection of states such as "The United States".
     My uncle lives in Cumbria near Lake Windermere.
Use an article with bodies of water, oceans and seas -
     I live on a small island in the Baltic Sea.
DO NOT use an article when you are speaking about meals, places, and transport
I go to university.

exaples

Eric has a dog.
Gregory works in a factory.
Can I have an apple?
Donata is an English teacher.
The car over there is fast.

The teacher is very good, isn't he?

exercises

Can you tell me how to get to ___ cinema from here? 
___ college is closed today.
Gregory is one of ___ strangest people I know.
I recommend you try ___ tomato soup at this restaurant.
___ beer is good for you.
Would you like to see ___ film?
___ apple a day keeps ___ doctor away.
I can't believe I failed ___ yesterday's test!
Do you have ___ dictionary that I can borrow?
There were many dogs in the park. One dog was ___ Dalmatian.
Pandas and ___ tigers are both endangered animals.
Magda is wearing ___ blue dress with red shoes
Bornholm is ___ island in the Baltic Sea.
Christmas comes once ___ year.
___ owl is __ bird.
The Severn is ___ river.