This area is a no-entry area.

The success of this project is still uncertain.

His disloyal actions deeply hurt his friends.

Fujitsuko is my best friend.

This compound is an unsaturated hydrocarbon.

This chemical reaction is irreversible.

His unwavering determination became the power to overcome all difficulties.

Invisible light rays are not visible to the human eye.

He made an indiscreet remark and troubled those around him.

His indiscretion greatly damaged his reputation.