Allowing the pairing of each member of a class uniquely with a member of another class.
一对一的让这一组的成员和另一组的成员一一匹配的
A collection of data in which each item is uniquely identified by a label, by its position relative to the other items or by some other means.
数据的一种集合, 其中每一项可唯一地被一个标号或相对于其它项的位置或某些其它方法所标识。
