Demand is decreased.
Demand has decreased.
He is gone back to the hotel.
He has gone back to the hotel.
She was arrived an hour before.
She has arrived an hour before.
The lecture is begun.
The lecture has begun.
Your child is grown a lot.
Your child has grown a lot.
Your English is improved.
Your English has improved.
The director had made to resign.
The director was made to resign.
The criminal was arrested by the police.
The police had already arrested the criminal twice before.
The project was finished on time.
The project had already finished when I joined the team.
Taxes were increased by 20% by the new government.
The problems have increased over the last two years.
The patient was taken to the hospital in an ambulance.
The father had taken the children to school.
is / was / will be etc + past participle - passive form (the child was caught smoking - it is not the child that does the action of catching but the teacher).
has / have / had + past participle - present perfect or past perfect form (the teacher had already
caught the child smoking several times before - the teacher does the action of catching).