The experiments had been done on briefly soaked rocks.

这些实验是在简单浸泡的岩石上做的。

He got home to find that his flat had been done over.

他到家后发现公寓里被盗了。

She knew it would be difficult to undo the damage that had been done.

她知道难以挽回已造成的损失。

I couldn't make out how it had been done.

我原来还不明白这是怎么回事。

Our waste recycling project involving a lot of investigation and paperwork had been done by the end of last term.

我们的废物回收项目已经在上学期末完成了，其中包含许多调查研究和书面工作。