Definite or indefinite article?

Which of these determiners do we have to use, a , an, or the or the "zero" article?
It's a good question. So in order to refresh your minds, I invite you to have a look at this web site which explains the differences you're looking for and provides you online exercises.

http://depts.gallaudet.edu/englishworks/grammar/main/articles.htm

You also can do this additional exercise...
http://www.learn4good.com/languages/evrd_grammar/article_ex2.htm













Enjoy them and have a FUN moment! ....