thirtieth是什麼意思

例句：

1、A day is about one thirtieth of a month.

一天大約是一個月的三十分之一。

2、One second of arc movement is one thirtieth of a millimetre.

一弧秒的移動是一毫米的三十分之一。

3、The current contract with the actors union ends June thirtieth.

目前其與演員工會的.合同將在六月三十結束。

4、The last day in September is the thirtieth.

九月的最後一天是三十日。

5、Thirty-three thousand people think that Thursday is their thirtieth birthday.

三萬三千人認為星期四是他們三十歲生日。