1. Mike wants to go back to the supermarket. He says:
'I have forgotten to buy milk'    
'I forgot to buy milk'   

2. You ask Sally if she wants to go to the cinema. She says:   
'Sorry, I'm visiting my mother this evening'    
'Sorry I have been visiting my mother this evening'   

3. You ask the waiter for a beer. He replies:
'I'm sorry we ran out of beer.'    
'I'm sorry, we have run out of beer.'   

4. You ask to speak to Mr Wilson. His secretary says:
'He went out ten minutes ago.'    
'He has gone out ten minutes ago'   

5. You ask to speak to Mr Wilson. His secretary says:
'He has been out for the last ten minutes'    
'He went out for the last ten minutes'   

6. You ask to speak to Mr Wilson. His secretary says:
'I'm sorry, he went out'    
'I'm sorry, he has gone out'   

7. You are leaving a party. You tell your host:
'Thank you. I had a wonderful time.'    
'Thank you. I've had a wonderful time.'   

8. You ask about an old friend. Someone tells you:
'She has had a baby. He's six months old now'    
'She is having a baby. He's six months old now.'