你是不是也常常抬头望天？从降雪量的测定到西藏的星空，这些看似无关的自然现象，其实都是地球给我们的“小纸条”。为什么我们要费心去测量降水？不就是想知道...
Introduction English is a universal language that is spoken and understood by people all over the world. It is considered to be the official or se...
