序数词是: thirtieth，缩略形式:30thBy sunset we had covered thirty miles.

到日落时我们已走了三十英里。

Some thirty people attended the funeral.

大约有三十人参加了葬礼。

She thinks nothing of walking thirty miles a day.

她认为一天步行三十英里不足为奇。

She's in her mid-thirties—thirty-six to be exact.

她三十五岁…