氮气可以大量、稳定地存在于空气中的原因是( ) A 氮气比空气稍轻 B 氮元素的非金属性比氧元素的非金属性强 C 氮原子的半径比氧原子的半径大 D 氮分子中存在共价叁键,破坏它需要很大的能量 答案:D---________( )---I like donuts for lunch.A. What is your favourite food for breakfast?B. What is your favourite food for lunch?C. What is your favourite food for dinner?