beautiful:more beautiful,the most beautiful
slowly:more slowly,the most slowly
thin:thinner,the thinnest
beautiful:This flower is more beautiful tham that one.
This picture is the most beautiful one I have ever seen.
slowly:I move more slowly while riding a bike than driving a car.
Perhaps turtles are the most slowly animals in the world.
thin:She is thinner than me because she love sports.
She is the thinnest student in our class.