Verified answer

1. How long have you been learning English?

2. They have already been watching TV for 40 minutes.

3. He has been cooking supper for nearly three hours.

4. How long has she been dating your brother?

5. They have been cycling for two hours.

6. You have been playing computer games too long. Your eyes are red.

7. Why have you been crying?

8. He was listening to music the whole morning. Или He has been listening to music the whole morning (если утро еще не закончилось)

9. It has been snowing for three days.

10. He has been learning to play the guitar for two weeks.