Salam!
Every year, the pps ask me the same question about adjectives:
"How can we know if the adjective is long or short?"
Sometimes an adjectives can undergo both rules: of long and short adjectives.
eg. handsome handsomer or more handsome.
Both are correct and the adj. contains two syllables.
For this, I felt obliged to make a little research, last year, to give the pps a clear idea about this point and to make them afford a reference for the years to come.
Here is the link:
http://www.mediafire.com/?owzmkjiznwj
Wish you'll find it useful and ready to accept any comment.
Salam!