阅读下面短文，将文中划线句子译成中文。
　　Some kids in boarding school often like to talk with their roommates. ____ They won’t stop talking until someone comes to stop them. This is the reason why many of them are sleepy in class the next day. Lack of (缺乏) sleep is bad for their health. Growth hormones (生长激素) are very important if one is to grow taller. ____ The body makes the most hormones between 10 p.m. and 2 a.m. While you are asleep. ____ This means that if you don’t get to sleep at the time, you won’t grow taller.

①三种投资产品的风险由小到大有可能为丙<乙<甲

②在储蓄、保险、股票这几种方式中，甲产品可能是保险

③如果乙产品是金融债券，则甲产品可能是政府债券

④如果丙产品是金融债券，则乙产品可能是企业债券

下列属于哺乳动物特有的特征是（　　）