Ответ:
1. A: Can we swim on this beach?
B: No, we can't. The sea could be dangerous here.
2. A: Can you play tennis?
B: Yes, I can, but I only learnt to play this year.
I couldn't play at all last year. I was terrible!
3 A: Could you walk when you were one year old?
B: Yes, I could, but my sister couldn't walk until she was one and a half.