1. When I was in school, we learned "黑人" as "Negro", not "the black:". If you call a "黑人" as Negro in Queens Dist, New York, you are a dead man.
2. When I was in school, we learned "农民" as "peasant", not "farmer". And now we know "peasant" is a title of insult.
3. When I was in school, we learned "橡皮" as "rubber", not "eraser". And now we know "rubber" means "condom".