He is traveling around the world in search of the elixir of life.

He is undergoing training for extravehicular activity.

He engaged in an extravehicular activity from the spaceship.

He is studying about ancient military tactics.

This is a linear mathematical problem.

This equation is linear.

They waged war against the enemy country.

The judge delivered a guilty verdict to him.

The judge sentenced him to life imprisonment.

He acted as the spearhead of our team.