_____ is the first element on the periodic table, making it the lightest element. Since it is so light, it rises in the atmosphere and is therefore rarely found in its pure form.

解析: 【解析题】拼音文字都经历了辗转借用的过程,并且保存了造字的理据。 【解析题】关于冠心病的描述不正确的是 […]