1. Madame Curie will always be remembered as the discoverer of the element radium.
    居里夫人这位镭元素的发现者,将永远为人们所怀念.

2. Radium is a radioactive element.
    镭是个放射性元素。

3. Radium and uranium are radioactive elements.
    镭和铀是放射性元素.