1. Comparative & superlative
One-syllable adj. tall taller than as tall as less tall than the tallest
3+- syllable adj. interesting more interesting than as interesting as less interesting than the most interesting
2+- syllable adj. doubtful more doubtful than as doubtful as less doubtful than the most doubtful
ending –ful & -re obscure more obscure than as obscure as less obscure than the most obscure
2+- syllable adj. clever cleverer than as clever as less clever than the cleverest
ending -er, -y, -ly silly sillier than as silly as less silly than the silliest