题目

—How I wish everyone were kind and respected their elders! —________，there wouldn't be quarrels among the parents and their children. A．When necessary  B．If so C．If possible  D．So what 答案：B下列能源中既属于一次能源又属于可再生能源的是 A. 太阳能          B. 核能           C. 石油          D. 天然气