题目

Mr. King didn't know _______ yesterday evening. A . when does his son come home B . when his son comes home C . when did his son come home D . when his son came home 答案：D当两个具有相同资源利用方式的种群占有同一生境时，最有可能发生（    ） A．竞争    B．突变    C．种内斗争   D．共生