题目

阅读理解 A new study of 8,000 young people in the Journal of Health and Social Behavior shows that although love can make adults live healthily and happily, it is a bad thing for young people. Puppy love, (早恋) may bring stress for young people and can lead to depression. The study shows that girls become more depressed than boys, and younger girls are the worst of all. The possible reason for the connection between love and higher risk of depression for girls is “loss of self”. According to the study, even though boys would say “lose themselves in a romantic relationship”, this7．汽车是常见的一种交通和运输工具．请你运用已学过的物理知识解释：油罐车的尾部为什么要拖一条铁链？