In most instances, the observer is the senior investigator and the only  Margaret Mead in Samoa and Oscar Lewis in Puerto Rico are famous examples.
The observer is a senior investigator.
The observer is a brief observer.
People are playing sports.
child is playing chess board.
The woman is exiting the dragons mouth.
The reputation of Las Vegas has changed over the years.
Women approach a hydrant.
I'm off and on but I go to the fitness center.