完整形式是fourth，例如：

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。