two dirt bike riders ride their dirt bikes.
The two riders rode their dirt bikes.
The two motorcycle riders ride their motorcycles.
They don't watch any game that's on because they do not like sports.
Dr. Demento runs for president.
A man in an apron is making a pot of coffee.
It is very easy to challenge established systems, as there are no opponents.
Jon didn't fully understand her.
A black dog is doing a backflip.