Passive: Nine anonymous letters were mailed to me.
Active: I received nine anonymous letters.
Passive: Veronica was promoted.
Active: Management promoted Veronica.
Passive: The cause of the problem is unknown.
Active: The investigators do not know the cause of the problem.
Here’s what Joseph M. Williams has to say on the topic on page 80 in Style: Ten Lessons in Clarity and Grace:
Choose the passive voice when you don’t know who did it, your readers don’t care who did it, or you don’t want them to know who did it.
Well said. The choice is yours, but remember—active voice is generally more powerful, clear, and concise.
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