如果集合较小，我们可以简单地列出起成员并用正整数记录列出的成员的数目，从1开始，以自然数的次序往下直至结束。

If the set is small, we can simply list the members and number the list with positive integers, starting with 1 and proceeding in the natural order until we reach the end of the list.

youdao

如果集合较小，我们可以简单地列出起成员并用正整数记录列出的成员的数目，从1开始，以自然数的次序往下直至结束。

If the set is small, we can simply list the members and number the list with positive integers, starting with 1 and proceeding in the natural order until we reach the end of the list.

youdao