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Random things I remember about the book:
The boy is abducted from Earth to join an intergalactic space school or academy.
I remember a scene near the beginning: he saw a young girl and was mesmerized by her, but was suddenly stopped by another student/cadet/teacher saying "be careful, they eat their own".
The girl later has some sort of breakdown and they are forced to wipe her memory and return her home.
The protagonist remarked how they operated on his tongue so he could speak the common language.
In another scene the aliens had removed the bacteria from under his arms saying that the smell bothered the other people and offered to return it.
I think the cover was vintage 70s-80s and had a drawing of the boy in a space suit with a few of the other students standing in a distance behind him.
I don't remember what the plot was. It may have just been how he was settling in to the new life.
It it not the following books: Ender's Game, Pattern's of Chaos, The Last Starfighter, Tompopaageo