What is a simple sentence using the word an?
Use "an" anytime you would use the word "a" if before a word starting with a vowel. If the next word is "test" you would use "a", if the next word is "exam" you would use "an". A test, an exam. Now you should know how to do this for yourself.
I've got AN amazing idea. :D hope this helped!
Would you like an egg