Complete the sentences with can, can’t, could or couldn’t.
1)When he was young, my grandfather ...... (run) 12 kilometres.
2) John can’t run very fast but he ...................... (jump) high.
3) I ............... (finish) my homework last night, I was too tired.
4) The dog hurt its leg and it ...................... (walk).
5) ............. Tony .................. (find) his way to the party tonight?
6) Sorry I ...................... (not help) you paint your house yesterday.