根据句意, 用括号内所给单词的适当形式填空。
Some serious disease may break out in this________ (heavy) polluted area one day.
In order to get a perfect result, some more________ (value) steps should be taken.
Though many basketball players are tall, one does not have to be tall to ________ (success)  in NBA.
Steven Spielberg, one of the most famous ________ (direct), showed his film talent by  making short films when he was still a teenager.