Well, I guess air pollution is the most serious. The sky is not blue any longer. Instead, it's always gray. You will have difficulty in breathing?

呃，我想空气污染是最严重的。天空不再是蓝色的，反而总是灰蒙蒙的。你呼吸的时候会有困难。

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Here, the sky and white clouds are so close; the sunshine and air is so transparent; hills and water are so blue. I had the famous snacks and visited well-known attractions.

在这里，天空和白云如此接近，阳光和空气无比通透，明丽的青山绿水一如浓妆艳抹，吃那些听熟了的云南小吃，逛那些听熟了的著名景点。

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Well, know once for all that the blue vault of the sky is only an appearance due to the air which envelops us, and which, owing to the thickness of the envelope, has a beautiful blue color.

其实，蓝色的天顶只是环绕我们的空气，只不过因为它是厚厚的一层，才有了美丽的蓝色。

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