This is a long river.

这条河很长。

I can see a river, a long river.

我看见了小河，长长的小河。

He is waling along the long river.

他沿着长长的河流走着。

And then, you see is the long river.

然后呢，你看到的是很长的河。

The human history is like a long river.

人类历史像一条长河。