thirteen 十三；

thirty 三十；

例句：

He ran away from home at the age of thirteen. 他十三岁时离家出走。

By sunset we had covered thirty miles. 到日落时我们已走了三十英里。

During the expedition, they trekked ten to thirteen hours a day.

在探险期间，他们每天都要走十到十三个小时。

Lewis is the author of thirteen novels and ten nonfiction books.

路易斯写了十三部小说和十本纪实作品。

Thirteen years ago she found herself having to conjure a career from thin air.

十三年前她认识到自己得白手起家闯出一番事业来。

only thirty students graduated in Chinese last year.

去年只有三十名学生获得汉语学士学位。

The driver was a trim young woman of perhaps thirty.

驾车者是一位大约三十来岁的苗条年轻女子。

If I might hazard a guess , I'd say she was about thirty.

让我来猜的话，我说她大约三十岁。