thirty和thirties的区别

thirty:

n. 三十年代

num. 三十

adj. 三十个的

I usually do my homework at around five thirty.

我通常5点半左右写作业。

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。