Nowadays more and more people are using modern traffic and modern communication means. The world ____ (it) is becoming much smaller. So life today is much easier than it was ____ (hundred) of years ago. but it has brought new ____ (problem). One of the biggest problems is pollution. To pollute mean to make things dirty. Pollution comes ____ many ways. We see it, smell it, drink it and even hear it.

    Air pollution is still the most serious. It's bad to all living things in the world, but it is not the ____ (bad) one kind of pollution. Water pollution kills our fish and pollutes our drinking water. Noise pollution makes us become angry more ____ (easy).

    Pollution by SO₂ is really the most dangerous problem of air pollution. It is ____ (cause) by heavy traffic. It is true that ____ there are fewer people driving, there will be less air pollution.

    The earth is ____ (we) home. We must take care of it. That means ____ (keep) the land water and air clean. And we must take care of the rise in pollution at the same time.

观察下列图形及图形所对应的算式，根据你发现的规律计算1+8+16+24+……+8n（n是正整数）的结果为(         )

将下列陈述句改成疑问句。

①这样死了，比鸿毛还轻。

②功课没做完，不能去看电影。