jaqovious 2020-11-21T09:46:35+00:00 [img]https://img.nga.178.com/attachments/mon_202011/21/-7Q5-f92dK1hT1kShs-12i.jpg.medium.jpg[/img]太难了吧[s:ac:呆]。列出方程，三个未知数量关系，还要用选项往里一个一个试