Fill in : can, could or be able to in the correct tense.
John: 1)Can you ski?
Dave: Yes, l 2)... I went skiing last year and l 3).... go down the learner's slope easily.
John:l 4).... ski when I was younger, but since I hurt my leg l 5)....
Dave: Actually, I think ice-skating is much easier. I 6)....
John: Really? I tried ice-skating once, but I 7).... ice-skate when I was five years old. stand up at all!