He was involved in the development of guided missiles.

I avoid eating animal products.

This semi-automatic washing machine is easy to use.

This copper pot is an ancient craft.

He is working in the animation industry as an inbetweener.

I want to learn how to use potential verbs.

He can write sentences using potential verbs.

He is lobbying to influence politicians.

Heliocentrism is the theory that the sun is the center of the universe.

Using auxiliary verbs makes the meaning of the sentence clearer.