1. Suppose you were born in 1800, how would you measure the mass of the Earth? 额……在课堂上听老师提过……但是没有带书回家……当时这个内容也只是作为了解……没想到假期作业会是这个orz求解救QAQ 要有实验步骤图片什么的能有书籍资料什么的更好了#pm谢谢大家~#28m
