Whether the sound came from his head or from the hollow tree, that no one could say with certainty.

没有人能肯定地说，这声音是从他的脑袋里发出来的呢，还是从空树里发出来的呢？

youdao

From a very large owl, in a hollow tree; a sort of learned owl, that continually knocked its head against the branches.

这只猫头鹰的脑袋里装的全是智慧。它不停地把脑袋撞着树。

youdao

At last, tired out with hunger and sorrow, and the long journey, they crept into a hollow tree, laid themselves down, and slept till morning.

最后，又累又饿又悲伤，走了这么远的路，他们爬进了一个树洞，躺下来，一直睡到了天亮。

youdao

It takes place in a large hollow tree.

VOA: special.2009.11.27

Using a hollow tube, they drill into the tree and extract a 5-mm wide cylinder that shows each ring starting with the most recent, just under the bark.

VOA: standard.2010.04.05