Fill in the blanks with the Present Perfect Continuous of the verbs in brackets.
1. Mary а(play) trompet since half past three.
2. How long а(John/study) for the exam?
3. Whereаа(she/live) since then?
4. Michael а(sleep) for two hours.
5. Jane а(work) in the supermarket since half past ten and she is still there.
6. Those chemicals а(pollute) our rivers and rivulets.
7. а(they/not/live) in London lately?
8. What а(you/do) for the last two hours?
9. The childrenаа(play) outside.
10. She а(do) the homework since she arrived home.