21. There is no denying the fact that air pollution is an extremely serious problem： the city authorities should take strong measures to deal with it.
22. An investigation shows that female workers tend to have a favorable attitude toward retirement.
23. A proper part-time job does not occupy students\' too much time. In fact， it is unhealthy for them to spend all of time on their study. As an old saying goes： All work and no play makes Jack a dull boy.
24. Any government， which is blind to this point， may pay a heavy price.
25.Nowadays， many students always go into raptures at the mere mention of the coming life of high school or college they will begin. Unfortunately， for most young people， it is not pleasant experience on their first day on campus.
26. In view of the seriousness of this problem， effective measures should be taken before things get worse.
27. The majority of students believe that part-time job will provide them with more opportunities to develop their interpersonal skills， which may put them in a favorable position in the future job markets.
28. It is indisputable that there are millions of people who still have a miserable life and have to face the dangers of starvation and exposure.
29. Although this view is wildly held， this is little evidence that education can be obtained at any age and at any place.
30. No one can deny the fact that a person\'s education is the most important aspect of his life.