Using active voice when passive is needed, or forming the passive structure incorrectly.
Structure: Be + V3 (Past Participle). Used to emphasize the receiver of the action rather than the doer.
The house built in 1990.
The house WAS BUILT in 1990.
In Academic Writing, the passive voice helps maintain an objective tone (e.g., 'It is believed that...' instead of 'People believe...').