cardinality of a set

• 集合的基数

cardinality of a set的用法和样例：

例句

1. The base for an index is set when it is created.
   一个指数的基数确定后就固定下来。
2. There's not a large enough base of workers to support them.
   现在的工人的基数不够大，不足以维持他们的生计。