IV.
21. a -> an
22. polluted -> pollution
23. noisy -> noisier
24. Lucky -> Luckily
25. learning -> to learn
V.
26. visit her friend because she doesn't have time.
27. how much I thought it would cost.
28. gone aboard before.
29. been used for three months.
30. is considered to be one of the best.
IV:
21. an hour
22.
23. noisier
24. Luckily
25. to learn
V:
26.
She won't visit her friends because she hasn't time.
27.
He asked me how much I thought it would cost.
28
He hasn't gone abroad before.
29.
That computer has been used for 3 months.
30.
His speech was considered one of the best
