—If people make small changes, like taking buses instead of driving cars, it will make a big difference. —_____. Then the traffic will be much better.
32. Once he starts a job, he won’t stop ______ it’s finished.
31. An e-pal, as you have known, means a friend ______ you write e-mails.
30. He will not tell the fact ______she has gone to Beijing.
29. The film is ______ a film. It is also a good material for education.
28. The water will be further polluted unless some measures ______.