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00000001hydrogen is a chemical element with chemical symbol H and atomic number 1. With an atomic weight of 1.00794 u, hydrogen is the lightest elem0Antarctica is Earth's southernmost continent,containing the geographic south pole,it is situated in the Antarctic region of the southern0A dual economy is the existence of two separate economic sectors within one country divided by different levels of development,technology,an0Motion is a change in podition of an object with respect to time.Motion is typically described in terms of displacement,distance ,velocity,a0亲爱的各位吧友:欢迎来到南极洲总司令