For every tree cut down, three or four new ones are planted.

每砍倒一棵树就要种上三四棵树。

《新英汉大辞典》

That's much simpler than going up three parent directories, and then heading back down the directory tree or using the absolute path.

这比向上三个父目录，然后沿目录树向下，或者使用绝对路径要简单得多。

youdao

Three or more tables nested into a tree structure.

个或更多表嵌套在一个树结构中。

youdao

As I was walking into work this morning, I saw an evergreen that's probably got a tree trunk two or three feet in diameter that was completely on its side.

NPR: Fires in Texas, Fierce Storms in Midwest

In those areas that have had three or four periods of experimental burning only half the number of species of tree seedlings originally found are still there.

ECONOMIST: A new experiment is setting the Amazon on fire