In any list, put commas between the items but “and” between the last two items, generally without a comma, e.g. I saw the boy and the girl together. I went to the shop to buy butter, meat, bread, jam and tomato sauce.
ISLPR Language Services Blog
Do you know the difference? These three words are homophones and they confuse many people.
Use _er, _est if the adjective has one or two syllables, e.g. happy, happier, happiest; high, higher, highest.
Positive degree: high
Comparative degree: higher
Superlative degree; highest
Use more or most if the adjective has more than two syllables, e.g. beautiful, more beautiful, most beautiful.
There are also some words that have special comparative forms, e.g. good, better, best; bad, worse, worst.