the fourth one is mine.意思是第四个是我的。fourth是序数词，意思是第四的，第四。常做定语。例如the fourth monkey第四只猴子。它一般不单独使用，与the及名词搭配使用。若要单独使用时，用在排列的场合：一般陈述观占时，first， second， third， fourth…并列使用。
fourth的造句如下
1、
He is beginning his fourth consecutive term of office.
他开始了第四届任期。
2、
This was the fourth album by the top rock outfit.
这是这个顶级摇滚乐队的第四张唱片专辑。
3、
The 800 metres is the fourth event of the afternoon.
800米赛是下午的第四项比赛。
1、He himself bad only finished the fourth grade.
They hit pay dirt on the fourth day.
