Use “can” if possible; otherwise use “be able to”.
1. George has traveled a lot. He … speak three languages. 2. Martin is an
eccentric. I’ve never … understand him. 3. Tom might … come tomorrow. 4.
Sandra … drive but she hasn’t got a car. 5. I’m very busy on Friday but I …
meet you on Saturday morning. 6. Ask Catherine about your problem. She
might … help you. 7. I would like to … swim well. 8. She used to … dance
very well but she … not do it now.