Comparative: shorter, longer, more rare, more agressive, more intelligent, better, stronger, older, younger, heavier, more sociable, worse, better.
Superlative: the biggest, the lightest, the heaviest, the most aggressive, the most peaceful, the proudest, the oldest, the youngest, the longest, the shortest, the most adventurous, the best (you have it correct), the worst (also correct), the strongest, the smallest, the most common, the best (cette réponse était correcte aussi) :)
