Réponse :
Bonjour,
1)The MET is ( interesting ) museum in New York.
The MET is the most interesting museum in New York.
( interesting adjectif long ---> the most + adjectif )
2)( famous ) monument in the United States is surely the Statue of Liberty.
The most famous monument in the United States is surely the Statue of Liberty.
( famous adjectif long ---> the most + adjectif )
3)Visiting New York in October is certainly ( good ) choice.
Visiting New York in October is certainly the best choice.
( good adjectif irrégulier -----> the best )
3)Mount Rushmore is ( tall ) mountain in the USA.
Mount Rushmore is the tallest mountain in the USA.
( tall adjectif court -----> the + adjectif -est )