What is the source of this information?

The fountainhead of this river is at the top of the mountain.

Mr. Xi is my best friend.

He dug a pit in the garden.

This bug is very small, isn't it?

His words always resonate in my heart.

Beautiful ornamental trappings were decorated under the collar of his kimono.

The green sea turtle spends a long time in the sea.

In Japanese grammar, predicates are part of independent words and can be inflected.

Understanding the structure of atoms is a fundamental part of physics.