thirty是什么***数字？thirty和thirties的区别？

 详细的说是29与31之间的独一一个天然数、正整数，pl.三十几；三十年代My father has been the President of the company since he was in his thirties.我父亲三十几岁就是公司的董事长了。同类词:

        thirty所指的***数字：30（三十）！详细的说是29与31之间的独一一个天然数、正整数，是一个偶数，也是一个有理数。30=2*3*5。

thirty:

n. 三十年代

num. 三十

adj. 三十个的

I usually do my homework at around five thirty.

我凡是5点半摆布写功课。

thirties:

pl.三十几；三十多岁；三十年代

My father has been the President of the company since he was in his thirties.

我父亲三十几岁就是公司的董事长了。

同类词: seventy, eighty...

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

她三十五岁摆布—切当地说是三十六岁。

He was struck down by cancer at the age of thirty.

他三十岁那年被癌症夺去了人命。

He died seventy years ago.

他70年前就死了。

I hope I am still healthy when I am in my seventies.

我希望本身七十多的时候仍然安康。