George has travelled a lot. He *** speak four languages. (can/be

George has travelled a lot. He *** speak four languages. (can/be able to)
I haven't *** sleep very well recently. (can/be able to)
Sandra *** drive but she hasn't got a car. (can/be able to)
I can't understand Martin. I've never *** understand him. (can/be able to)
I used to *** stand on my head but I can't do it now. (can/be able to)
I can't see you on Friday but I *** meet you on Saturday morning. (can/be able to)
Ask Catherine about your problem. She might *** help you. (can/be able to)