His father is a very strict person.

During the Yuan dynasty, Chinese culture developed greatly.

This is my original.

Understanding the original principle is important for solving problems.

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.