交作业：

阿拉斯加或许看似遥远纯净，但是地球上没有一个地方可以免受空气的污染，环境的污染，和影响我们所有人的全球变暖问题。

Alaska may appear distant and pure， but there is no single place on Earth to be shielded from air pollution, environmental pollution, and the problem of global warming which may impact all human beings.