Two dancers practicing together.
Two people pratice a sport.
A group of people play rugby outside.
I kept it unlocked.
Children eat a watermelon.
Tenure, fame, and public good--the last three motives, they don't fit as well with the basic assumptions of economics.
The girl is helpiing out.
They had all been to Prague before, and knew all about its wonders.
A woman is quietly talking to a stranger who is standing by some water.