题目

The evidence for harmony may not be obvious in some families. But it seems that four out of five young people now get on with their parents, which is the opposite of the popularly held image (印象) of unhappy teenagers locked in their room after endless family quarrels. An important new study into teenage attitudes surprisingly shows that their family life is more harmonious than it has ever been in the past. “We were surprised by just how positive today’s young people seen to be about their families,” said one member of the research team. “They’re expected to be rebellious(叛逆有资料反映，测量人体血液的密度可以采用如下方法：先在几个玻璃管中分别装入密度不同的硫酸铜溶液，然后分别在每个管中滴入一滴待测血液，检验人员只要看到哪一只管中的血液悬浮在其中，就能判断血液的密度．根据上述资料的启发，利用天平（含砝码）、量筒、烧杯、水、玻璃棒、盐水来设计一个实验方案，测量一粒花生米（密度略大于水）的密度．要求：写出具体的测量步骤和花生米密度的表达式．