I waited upon him at the restaurant.

She waits upon her guests with great hospitality.

Let's touch upon that topic in our next meeting.

Upon a sudden, the door burst open.

He stumbles upon a hidden treasure in the forest.

The school frowns upon cheating.

The group of friends rounded upon the stranger who was following them.

She has a sweet smile upon her face.

Lions prey upon weaker animals in the wild.

It finally dawned upon him that he had been wrong all along.