He saw the character '憂', and remembered his deceased friend.

Yuu believed in divine help from God.

Cold fusion is a part of physics and is a phenomenon that is not yet fully understood.

Research on cold fusion is still controversial.

Could you tell me your postal code?

Universal gravitation affects all objects on Earth.

This eigenfunction is one of the fundamental concepts of quantum mechanics.

Please put the letter in the post office box.

He thought deeply and said, 'I think, therefore I am.'

He strongly believes in the philosophical thought, 'I think, therefore I am.'