This tree is very hard.

He is a person with a strong heart.

He finished the job in slightly more than an hour.

Tsuyoshi is my best friend.

He is a very strong person.

His strength comes from his mental power.

Basic oxides react with acids to produce salt and water.

The basicity of this compound is very high.

There are a lot of old furniture in the storage room.

There are many things placed in my room.