We talked at length about the ceremony.我们就这个庆典谈论了很久。

The speaker went on at considerable/great/some length.演讲者滔滔不绝地讲了相当长/很长/好些时间。

No one was questioned at any length about it. [=no one was questioned for a long period of time]没有人被长时间询问。

The topic will be treated at length in the next chapter.这个话题会在下一章详尽论述。

The book doesn't discuss the topic at any length. [=the book only discusses the topic briefly]这本书只是简短地讨论了这个话题。

At length [=finally, in the end, at last], we decided to return home.最后，我们决定回家。