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.

法国前总理希拉克在参观陕西西安一个秦汉时期的文化遗迹后说：“世界上有七大奇迹。它的发现，使世界上有了八大奇迹。”这里的“第八大奇迹”指的是（   ）

一个科研小组计划检测一种新研制的环保型除草剂是否能有效地除草，他们选用了三块相似的草地进行实验．第一块草地喷洒传统的除草剂，第二块草地喷洒与第一块等量的新型除草剂，第三块草地不喷洒任何除草剂．几天后，发现第一块草地的除草效果良好，而第二块草地与第三块草地长势相似，那么下列判断中合理的是（　　）