thirtieth是什么意思

　　例句：

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

　　一天大约是一个月的三十分之一。

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

　　一弧秒的移动是一毫米的三十分之一。

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

　　目前其与演员工会的.合同将在六月三十结束。

　　4、The last day in September is the thirtieth.

　　九月的最后一天是三十日。

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

　　三万三千人认为星期四是他们三十岁生日。