题目

There isn't anything you do that can't be transformed into something interesting and uplifting. 答案：【1】你所做的任何事情都可以转变为有趣而激动人心的事情。氧气瓶的质量是5 kg,装入压缩氧气后总质量为6 kg,氧气瓶容积是10 dm3,此瓶内氧气密度是 ________________________kg/m3；若瓶内氧气用去了3/5,余下氧气的密度是 _____________________kg/m3。