The enemy aircraft invaded our airspace.

We are ready to invade enemy territory.

We are conducting training to devise strategies against hypothetical enemies.

The enemy general is approaching our camp.

Enemy troops are approaching our position.

He experienced his first encounter with the enemy on the battlefield.

He encountered the enemy on the battlefield.

He is a perfectionist, so he is very strict about his work.

He played a perfect fifth scale on the piano.

He said, 'It's difficult to make a life,' explaining the phrase 'When a man steps over the threshold, he has seven enemies.'