题目

物种是指能，并能后代的生物群体。骡是马和驴的后代，但骡不能繁殖后代，所以骡（填“是”或“不是”）一个物种。 答案：【1】相互交配【2】繁殖具有繁殖能力的【3】不是--Why did you laugh just now? --Ted wanted to tell us         very funny story, but he forgot           end himself． A．a; an                B．the; the            C．the; a            D．a; the