Study this example situation:

George is very old. Nobody knows exactly how old he is, but:
It is said that he is 108 years old.
or He is said to be 108 years old.

Both these sentences mean: 'People say that he is 108 years old.'

You can use these structures with a number of other verbs, especially:

• alleged
• believed
• considered
• expected
• known
• reported
• thought
• understood

• Cathy loves running.
  It is said that she runs ten miles a day. or She is said to run ten miles a day.
• The police are looking for a missing boy.
  It is believed that the boy is wearing a white sweater and blue jeans. or The boy is believed to be wearing a white sweater and blue jeans.
• The strike started three weeks ago.
  It is expected that the strike will end soon. or The strike is expected to end soon.
• A friend of mine has been arrested.
  It is alleged that he hit a policeman. or He is alleged to have hit a policeman.
• The two houses belong to the same family.
  It is said that there is a secret tunnel between them. or There is said to be a secret tunnel between them.

• It is reported that two people were injured in the explosion. or Two people are reported to have been injured in the explosion.

(Be) supposed to

• I want to see that film. It's supposed to be good. (= it is said to be good)
• Fireworks are supposed to have been invented in China. Is it true?

• The plan is supposed to be a secret, but everybody seems to know about it. (= the plan is intended to be a secret)
• What are you doing at work? You're supposed to be on holiday. (= you arranged to be on holiday)
• Our guests were supposed to come at 7.30, but they were late.
• Jane was supposed to phone me last night, but she didn't.
• I'd better hurry. I'm supposed to be meeting Chris in ten minutes.

• You're not supposed to park your car here. It's private parking only.
• Jeff is much better after his illness, but he's still not supposed to do any heavy work.