Marie Sklodowska Curie researched into the science of radioactivity(放射性).She is best known for discovering the radioactive elements—polonium and radium and as the only person to win two Nobel prizes.She did not patent her discoveries but made them available to everyone.She encouraged the use of X﹣rays for medical treatment.But she was not sufficiently aware of the dangers of radium and died of leukemia brought on by too much contact with radium.