题目

It just hadn’t been a very good week. On Tuesday, Sam’s father lost his job. Then on Wednesday, Sam’s mother announced that the rent（房租）on their apartment was going up. Now it was Friday, and Sam received an invitation from Rosa to her birthday party. Sam knew Rosa from Adventure（冒险）Club. He knew he would enjoy Rosa’s party, but he didn’t want to go without a gift. What could he possibly buy her with the little bit of money he had? Sam knew he couldn’t ask Mom or Dad for any money—not this week!Later that afternoon, Sam noticed a second-hand book sale going on. He下表是某报纸公布的世界人口数据情况：（1）表中有几个变量？（2）如果要用x表示年份，用y表示世界人口总数，那么随着x的变化，y的变化趋势是怎样的？ （1）表中有两个变量，分别是年份和人口数；（2）用x表示年份，用y表示世界人口总数，那么随着x的变化，y的变化趋势是增大． 【解析】试题分析：（1）年份和人口数都在变化，据此得到结论； （2）根据人口的变化写出变化趋势即可； 试题解析：【解析】 （1）表中有两个变量，分别是年份和人口数； （2）用x表示年份，用y表示世界人口总数，那么随着x的变化，y的变化趋势是增大．