Grammar revision

Can you tell the difference between the following pair of sentences?
Think about it and if you are not clear about any of them, ask me in the next revision class.

• He must be a good musician. 
• He must have been a good musician.

• He might not have existed.
• He can't have existed.

• You must have seen the film about King Arthur.
• You should have seen the film about King Arthur.

• You don't have to do it.
• You musn't do it.  

• I have lived in Barcelona for 10 years. 
• I lived in Barcelona for 10 years. 

• When Desi got home, her parents went to bed.
• When Desi got home, her parents had gone to bed.

• I'm going to paint my room.
• I'm going to have my room painted. 

• I wish I knew that.
• I wish I had known that.