其实树是范畴更广的图的特例。

A tree is actually an instance of a more general category called a graph.

youdao

影子是我们所想的，其实树才是真实的东西。

The shadow is what we think of it; the tree is the real thing.

youdao

其实树也是一种云，是绿叶做的云，是不怎么动的云。

But trees are clouds, too, of green leaves clouds that only move a little.

youdao