Question

According to The Elements of Style, which sentence is written in active voice?
The acceptance speech was given by the award winners.
The pennants were won by the championship team.
A memorable evening was had by all who attended the event.
The workers took precautions while digging along power lines.

Answer 1

"The workers took precautions while digging along power lines."

This is active voice — the subject ("The workers") performs the action. The others use passive constructions ("was/were ... by").