a radioactive gaseous element formed by the disintegration of radium; the heaviest of the inert gasses; occurs naturally (especially in areas over granite) and is considered a hazard to health
造句
用作名詞(n.)
Radon is the daughter of radium. 氡是鐳的子體。
Where does the indoor radon come from? 室內氡氣是從哪里而來?