的意思 countable set

1. A countable set is a set that can be put into a one-to-one correspondence with the set of natural numbers.
一个可数集合是一个可以与自然数集合建立一一对应关系的集合。

2. The set of even numbers is a countable set because it can be listed as 2, 4, 6, 8, etc.
偶数集合是一个可数集合，因为它可以列出为2、4、6、8等。

3. The countable set of prime numbers includes 2, 3, 5, 7, 11, and so on.
可数质数集合包括2、3、5、7、11等。

4. The set of integers is a countable set since it can be arranged in a sequence of 0, 1, -1, 2, -2, 3, -3, and so on.
整数集合是一个可数集合，因为它可以按0、1、-1、2、-2、3、-3等顺序排列。

5. A countable set can be finite or infinite, as long as its elements can be counted one by one.
可数集合可以是有限的或无限的，只要它的元素可以逐一计算。

6. The countable set of all positive fractions can be represented as 1/1, 1/2, 1/3, 2/1, 2/2, 2/3, and so on.
所有正分数的可数集合可以表示为1/1、1/2、1/3、2/1、2/2、2/3等。