Insulin was first discovered in 1921 by researchers at the University of Toronto. It is still a treatment available for diabetes.
An experimental solar power plant will be built in the Australian desert.
Mistakes were made.
Rules are made to be broken.
The cave paintings of Lascaux were made in the Upper Old Stone age.
You want to be vague about who is responsible.
The actor is unknown.
You want to emphasize the person or thing acted on.
You are talking about a general truth.
The actor is irrelevant.
