题目

阅读下面短文并回答问题，然后将答案写到答题卡相应的位置上(请注意问题后的词数要求)。 [1]Weighing too much can damage your health，and obesity is a growing problem for both kids and adults around the world． [2]Sleep might be one answer to the problem．A new study has found that elementary school students who slept too little were more likely to gain pounds． [3]Past studies have shown a link between sleeping less and weighing more，but scientists have had a tough time determining“which came first，the chicken or the egg，”says Julie C．Lu9．一个工厂原有煤x吨，烧了8天，每天烧a吨，还剩（x-8a）吨．