En superlativo, tienes que mencionar el grupo completo de comparación.
Peter IS the tallest OF THE class
Einsten IS the most intelligent OF ALL
The Lamborgini IS the fastest car OF THE Italian cars
My cousin IS the youngest OF THE family
Mexico City IS the biggest city OF THE country
Webster Dictionary IS the best OF THE English dictionaries
Lilly HAS the longest hair OF ALL my friends
The Mona Lisa IS the most famous OF ALL paintings in the world
This cocoa IS the hottest OF ALL in the cafetería
This IS the shortest man OF ALL the world
Ojalá te sirva...
