Simplify the following text for a Grade 11 native English-speaking person.
Original: From 1933 to 1939 he studied composition in Paris with Nadia Boulanger , and during World War II he worked as an interpreter for the Polish government in exile ( Szeryng was fluent in seven languages ) and gave concerts for Allied troops all over the world .
Simplified: Szeryng spoke seven languages fluently , so when World War II broke out he became an official interpreter for the Polish government which was based in exile in London .