It was the last day of the final examination in a university. A group of students entered the classroom happily. This was their last exam. They knew it would be easy. The professor had said that they could bring any book or note they wanted. The only requirement(要求) was that they couldn't talk with each other.
   The professor handed out the papers. They were glad to find there were only five questions. Three hours passed. The professor asked, "How many of you have finished all the five questions?" None of the students answered."How many of 3'ou have finished four?" No answers again. "Thee? Two?" The students moved restlessly (不安地) in their seats."One, then? Certainly somebody has finished  one." But the class remained silent. "That is exactly what I expected," the professor said. "I just want to teach you a lesson--although you have completed four years of study, there are still many things you don't know about." Then be added, "You will all pass the exam, But remember: even though you are graduating from college, your education has just begun."

乐平街上新开张了一家“好又多”超市，这个星期天，张明和妈妈去这家新开张的超市买东西，如图反映了张明从家到超市的时间t（分钟）与距离s（米）之间关系的一幅图：①图中反映了哪两个变量之间的关系？超市离家多远？②张明从家出发到达超市用了多少时间？从超市返回家花了多少时间？

③张明从家出发后20分钟到30分钟内可能在做什么？④张明从家到超市时的平均速度是多少？返回时的平均速度是多少？

读我国某地农村劳动力不同年龄段的迁移率(迁移率是指一定地区一定时期迁入迁出人口之和占该时期平均人口的百分比）柱状图，完成下列各题。

下列词语中,划线字的读音全都正确的一项是(    )

在同一平面内,两条不重合直线的位置关系可能是(   )。