We have already discussed this matter at great length.

我们已经十分详尽地讨论了这个问题。

He expounded his views on the subject to me at great length.

他详细地向我阐述了他在这个问题上的观点。

She told me what it meant at great length but I'm afraid I'm none the wiser.

她费尽口舌给我解释它的意思，可我恐怕还是不明白。

The chief objection to this book is its great length.

这本书的主要缺点是篇幅太长。

She rambled on at great length but she didn't get to the heart of the matter.

她夹七夹八地说了许多话也没说到点子上。