Too much passive voice is difficult to read. But here are three appropriate uses of passive voice:
The report was not prepared promptly.
All parents recognize the passive voice:
Derek’s ear got bitten!
The window got broken!
2. When the doer is obvious or unimportant.
Each visitor was given a meal ticket.
3. When you need to soften tone when active voice is too direct.
“Your check wasn’t enclosed.” is better than, “You did not enclose your check.”