Can/could - be able to can/is able to
ability in the present.
He can/is able to speak Spanish fluently.
opportunity to do something.
We can sit outside if you like.
could/was able to
ability in the past.
Ile could/was able to speak Spanish when he was ten.
ability in a specific situation in the past.
She was able to solve the puzzle in five minutes.
(NOT: she could...) (=She managed to)
Note: in questions and negations we can use either could or was able to.
will be able to
ability in the future.
He will be able to buy a new car as soon as he gets the money.​

1. I don't know what to give my brother for his birthday. 2. Do they want to publish this book in July? 3. She thinks he drives dangerously. 4. He understands that he eats noisily, but he always forgets about it. 5. Who is that man who is standing in the doorway? 6. I have no time now, I'm having dinner. 7. Does your family leave St. Petersburg in summer? – Yes, we always go to the seaside. We all like the sea. Mother stays with us to the end of August, but father returns much earlier. 8. Where are Tom and Nick now? – They are having a smoke in the garden. 9. What are you doing here now? – We are listening to tape recordings. 10. Do you want to see my father? – Yes, I do. 11. Michael knows German rather well. He wants to know English, too, but he has little time for it now. 12. What magazine are you reading? – It is a French magazine. There are good articles on sports here. Are you interested in sports? – Yes, I am, but I don't know French. 13. We are having an English lesson now. 14. He feels in a position to lend her money. 15. I think she doesn't feel safe there. 16. Do you see what I mean? 17. Do you hear what she is saying? 18. He doesn't feel at liberty to tell you the truth. 19. Ron has got a new job. He earns a fortune as a managing director. They think he is a bag of money.

1. I DON'T KNOW  what to give my brother for his birthday.
2. DO they WANT TO publish this book in July?
3. She THINKS he DRIVES dangerously. (Если вообще опасно водит, то есть в Present Simple) или She THINKS he IS DRIVING dangerously (если опасно водит на данный момент, то есть будет в Present Continuous).
4. He UNDERSTANDS that he EATS noisily, but he always FORGETS about it.
5. Who IS that man who IS STANDING in the doorway?
6. I HAVE no time now, I AM HAVING dinner.
7. DOES your family LEAVE St. Petersburg in summer? – Yes, we always GO to the seaside. We all LIKE the sea. Mother STAYS with us to the end of August, but father RETURNS much earlier.
8. Where ARE Tom and Nick now? – They ARE HAVING a smoke in the garden.
9. What ARE you DOING here now? – We ARE LISTENING  to tape recordings.
 10. DO you WANT to see my father? – Yes, I DO.
11. Michael KNOWS German rather well. He WANTS to know English, too, but he HAS little time for it now.
12. What magazine ARE you READING? – It IS a French magazine. There ARE good articles on sports here. ARE you interested in sports? – Yes, I AM but I DON'T KNOW French.
13. We ARE HAVING an English lesson now.
14. He FEELS in a position to lend her money.
15. I THINK she DOESN'T FEEL safe there.
16. DO you SEE what I MEAN?
17. DO you HEAR what she IS SAYING?
18. He DOESN'T FEEL at liberty to tell you the truth.
19. Ron has got a new job. He EARNS a fortune as a managing director. They THINK he IS a bag of money.