That person is my friend.

The big has the power to overcome the small.

His job title is a doctor.

His decision was considered arbitrary.

This problem is very difficult.

The difficulty of this problem makes me scratch my head.

This problem is so difficult to solve, it gives me a headache.

In this ancient document, the word 'urine' is used.

Many trees of the genus Castanopsis are planted in this park.

He began to feel numbness in his hand.