The most important birthday in the US is the eighteenth.

美国人最重要的生日是十八岁生日。

It really starts in the eighteenth century.

真正始于十八世纪。

Let me see. Not until the eighteenth of September, I'm afraid.

让我看一下。下次开课恐怕要等到9月18日。

Weren't there any other names available in the late eighteenth century?

十八世纪末就没有别的名字可用了吗？

She was going to talk with slides about our town amid eighteenth century.

她要用幻灯片讲我们镇子十八世纪的事儿。

However, in the late eighteenth and nineteenth centuries, social dancing became more popular.

但是，到了18世纪末期和19世纪，交际舞变得更加流行。

But the turning point in this story came along during my eighteenth birthday.

但是这个故事的转折点发生在我十八岁生日的时候。

Oh, thank you, my boyfriend bought it for my eighteenth birthday party.

噢，谢谢，这是我男朋友为了我18岁生日派对买的。

It starts in the eighteenth century, at least in Britain.

至少英国是这样的。

On the eighteenth, I wrote the first four pages of the “On Writing” section.

十八日我写了《论写作》部分的开头四页。