Answer:
The valuable jewels might have been stolen by someone, with the whole area monitored by TV cameras.
Hard hats must be worn by everyone when working on the building site.
He will have been told the news by next week.
He has never been told how to manage the club by anybody.
Active: They played a lot of old songs on the radio last week.
Passive: A lot of old songs were played on the radio last week.
Step-by-step explanation: