一天,我的邮箱收到一封来自XY星球的E-mail:亲爱的小凡,20多年过去了,你还好吗?我们XY星球的环境现在变得越来越差了。气候反常已经变得极端化,冬天和夏天都颠倒了过来,经常出现冬天气温高达五六十摄氏度,夏天气温降到零下四五十度的现象。你知道吗?因为以前我们没有好好珍惜水资源,致使星球上极度缺水,全球政府现在开始限制居民的用水量,我们每人每天只有两瓶用来饮用的纯净水,这二十几年几乎没有水可以给我们洗澡,整个星 One day, I received an email from XY Planet E-mail: Dear Xiaofan, more than 20 years have passed, how are you? The environment of our XY Planet is getting worse now. Climate anomalies have become extremes, reversing in winter and summer, often with winter temperatures as high as fifty or sixty degrees Celsius and summer temperatures falling to minus forty-five degrees. Did you know? Because we did not cherish the water resources before, resulting in the extreme water shortage on the planet. The global government is now beginning to limit the residents’ water consumption. Each of us has only two bottles of pure water for drinking everyday. No water can give us a shower, the whole star