Sure! Here are the completed sentences:

1. Gary has travelled a lot. He **can** speak five languages.
2. I haven’t **been able to** sleep very well recently.
3. Nicole **can** drive, but she doesn’t have a car.
4. I used to **be able to** stand on my head, but I can’t do it any more.
5. I can’t understand Mark. I’ve never **been able to** understand him.
6. I can’t see you on Friday, but I **will be able to** meet you on Saturday morning.
7. Ask Katherine about your problem. She might **be able to** help you.
8. You have to be careful in this part of the city. It **can** be dangerous.
9. Michael has lived in Italy a long time, so he should **be able to** speak Italian.