That plan is based on rational thinking.

Please research the interaction between these two drugs.

An old person was playing with his grandchild in the park.

Our school's motto is 'Knowledge is power.'

In Japanese, honorific language is an important way to show respect to others.

She is an expert in nursing.

He is always condemning others with abusive language.

He is a rationalist, making all decisions based on logic and facts.

This system is too irrational to understand.

I am surprised at the irrationality of this system.