his ninetieth birthday他的九十大寿

the ninetieth anniversary of the battle那次战役的九十周年纪念日

in ninetieth place排在第九十位

The fifth-best player in the world was matched against the ninetieth.世界排名第5的选手和排名第90的选手展开对决。

He finished ninetieth out of a hundred and twenty competitors.他最终在120名参赛者中排名第90。