Suppose 2

'Supposed to be' can be used to mean 'it is said/believed'.

• The new James Bond movie is supposed to be excellent.
• He is supposed to have been rude to Mark but I don't believe it.
• It is supposed to be the best restaurant in town.

'Supposed to be' can also be used to talk about what is arranged, intended or expected. It is a bit like 'should'.

• I'm supposed to get to work by 8.
• John is supposed to turn off all the lights when he leaves.
• I'm supposed to pay my rent on the first of the month.
• It's not supposed to be here.

Often there is a suggestion that the action 'supposed to' happen does not actually happen.

• I'm supposed to be there before 8 but I'm often late.
• You were supposed to phone me.
• I'm supposed to be getting on a plane to Tokyo at this very minute.

'Not supposed to' often suggests that something is not allowed or prohibited.

• You're not supposed to smoke in here.
• I'm not supposed to tell you.
• We're not supposed to use the Internet for personal reasons at work.
  

'Suppose' can also be used as a conjunction to mean 'what if'. Notice that the verb which follows it is sometimes, but not always, put 'more in the past'.

• Suppose we take the earlier train to Munich? It would give us more time there.
• Suppose we took the plane instead? That would give us even more time.
• There's nobody in reception to let our visitors in. Suppose I sit there until somebody comes?
• I'm going to ask him for a pay increase. ~ Suppose he said 'no'? What would you do?