78　a second和the second

1　a second 意为“又一个”，指“先提到一个后，又说起另一个”。

After I bought the shoes, the seller put a second pair on the shelf. 我买了鞋子后，售货员在架子上放了另一双。

The couple have a child and they hope to have a second . 这对夫妻有一个孩子，他们希望再有一个。

相同的用法还有：a third, a fourth, a fifth等。

2　the second 意为“第二”，表示先后顺序。

The second man to come was a singer. 第二个来的是一名歌手。

February is the second month of the year. 二月是一年中的第二个月。

相同的用法还有：the third, the fourth, the fifth等。