We can use the comparative form when we compare two people,place or things.
To form comparative,we use "er" or "more" but never the two together.
We use the superlative form when we compare three or more people,place or things.
E.g.
Apple is better than orange.
Banana is the best.
You are more beautiful than Kitty.
Mimi is the most beatuiful.
2008-01-03 17:56:32 補充:
若果一個英文字讀起來~多個三個音~~就用more and mostE.gBeautiful=bea~ti~fullcareful=ca~re~ful若果一個英文字讀起來~一個或二個音~~就用er and estclever=cle~verthin=thin