Rules for a/ an, some, any 
Short-answer quiz
by Julivan
http://fresno.cnice.mecd.es/~igam0003
Type your answer, then press "Check". If you need help, you can click on the "Hint" button to get a free letter.
We use ... with singular countable nouns.
We use ... with plural countable nouns.
We use ... with singular uncountable nouns.
In affirmative sentences, we use ...
In negative sentences, we use ...
In interrogative sentences, we use ...