Поставьте правильную форму глагола to be в предложениях, чтобы употребить Present, Past, Future Continuous:
1. I ... taking five courses this semester. 2. Bill ... trying to improve his English. 3. Sue ... writing another book this year. 4. John and Mary ... talking on the phone. 5. I need an umbrella because it ... raining. 6. We ... walking down the street when it began to rain. 7. It was beautiful yesterday when we went out for a walk, it ... not raining, the sun ... shining. 8. I couldn't get you on the phone last night, who ... you talking to so long? 9. What ... you doing at 6 tomorrow? 10. We ... playing chess in half an hour. 11. She ... listening to her favourite music at 8 o'clock tomorrow. 12. What ... you ... doing when I come?