E. Complete the sentences using Present Perfect Continuous.
20. It … for two days. (has been raining)
21. John … for two hours now! (has been sleeping)
22. How long have you been ... the environment problems? (studying)
23. She … to raise money for the zoo for months. (has been trying)
24. He … hard to build a nesting box, that's why it has already broken. (has not been working)
F. Fill in the question tag.
25. John is collecting rubbish, isn't he?
26. I could join the club too, couldn't I?