标题: 大全18题[求助] [打印本页] 作者: dydingding 时间: 2004-1-13 13:21 标题: 大全18题[求助] 18. A peculiar feature of the embryonic mammalian circulatory system is that in the area of the heart the cells adhere to one another, beating in unison and adopting specialized orientations exclusive of one another. (A) beating in unison and adopting (B) they beat in unison while adopting (C) beat in unison, and adopt (D) beating in unison yet adopting (E) even though they beat in unison and adopt