The key answer of exercise 9

A

1. 1 Where did you last have it?
2. I don't know. I used it last night when I bought a / my train ticket, so I must have had it then.
3. Have you used it since then?
4. No. I suppose I might have lost it on the train or I might have left it at home this morning.
5. Why don't you phone home and / to check?

B

1. 1 Where have you been? It's eleven o'clock!
2. I got stuck in (the / some) traffic.
3. Well, you should have phoned!
4. I'm sorry, I left my mobile phone at home.
5. But if I'd known you were going to be late (you'd be late), I could have gone to the pub.
6. I'm really sorry.