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。