1.C 祖先，祖宗　 any of the people from whom sb is descended, especially those more remote than his grandparents; forefather
2.C 原型；先驱　 early form of a machine or structure which later became more developed; forerunner

1. ancestor的基本意思是“祖先，祖宗”，是阳性可数名词，与其对应的阴性名词为ancestress[′ænsestrɪs]（女祖先）；引申可作“原型，先驱”解。
2. ancestor表示“…是…的祖先”时，须用介词to.

　a common ～　同一个祖先
　remote ～　远古祖先
　noble ～s　名门
　～ worship　祭祖

　She has worshiped her ancestor.　她已拜过她的祖先。
　This machine is the ancestor of the modern computer.　这台机器是现代电脑的始祖。

［同义词］ forebear
［反义词］ descendant