I've got two very good friends, Blanka  and Karina, and they are totally different. For example, Karina  is much taller than Blanka and she's  thinner too. She's also  more energetic and plays a lot of sport. Karina is generally more artistic. Her hair is  longer than Blanka's, and a bit  curlier. I don't think one is  more intelligent than the other - they are both clever and very nice people. But they are very different - sometimes I think Karina is a  better friend and other times I think Blanka is.



http://www.tinyteflteacher.co.uk/learning-english/grammar/exercises/comparative-adjectives.html

http://www.learnenglishfeelgood.com/english-comparative-adjectives1.html

http://s.mound.free.fr/skyblues67/comparing/trig&family1.htm