1. 表示"比...更"，用比较级形容词+than+比较成分，表示前者"超过"后者。than后主语的述语动词往往省略，非正式用法的than后的人称代名词可用宾格。
I am a better swimmer than you (are).
我游泳比你好。
But you are taller and stronger than I (am).
但是你比我高，比我壮。
Just because you are shorter and weaker, is that the reason you become a slower swimmer than me?
仅仅因为你比我矮比我弱，就有理由比我游得慢吗？
2. 否定的比较级表示"较...低；不及..."，用less+原级形容词+than+比较成分，表示前者不及后者。
I have always tried to help those who are less fortunate than I.
我一直设法帮助比我不幸的人。
At least you are less generous than I.
至少你没有我慷慨。