Y n.英语字母表的第25个字母(亦作y)；〈化〉钇(yttrium)abbr.(=yard；year)院子；年
详细释义
名词 duality:
being twofold; a classification into two opposed parts or subclasses
(physics) the property of matter and electromagnetic radiation that is characterized by the fact that some properties can be explained best by wave theory and others by particle theory
(geometry) the interchangeability of the roles of points and planes in the theorems of projective geometry
