杰克:

I think the biggest environment problem in my country is air pollution. 

我觉得我们国家最大的环境问题是空气污染。

凯西:

Yes, I agree. The air here is much more polluted than in my country. Of course, my country is more agricultural and has much less industry. 

我同意。这里的空气污染比我们国家严重多了。当然，我们国家农业比重比较大.工业比重比较小。

杰克:

We have reduced emission of air pollutants in recent years, but cars are still a major source of them. Factories have become cleaner as stricter environment pollution law have been introduced. 

我们这些年也在减少有害气体排放量，但是汽车废气排放依然是空气污染的主要原因.随着环境保护法的颁布。工业废气排放没有以前严重了。

凯西:

The problem is now on a truly global scale. I don`t believe that any single country can do anything about it. 

问题是现在的问题是个全球性问题。我不认为单凭一个国家的力量就能解决问题。

杰克:

I think you`re right. There needs to be an international response to this problem.?? 

你说得对。环境问题需要全世界的国家负起责任来共同合作解决。