某市团委举办“我的中国梦”为主题的知识竞赛，甲、乙两所学校参赛人数相等，比赛结束后，发现学生成绩分别为70分，80分，90分，100分，并根据统计数据绘制了如下不完整的统计图表：

电源与外电阻R连接成闭合回路，对于电源的路端电压U，下列说法正确的是（   ）

阅读理解

People communicate(沟通)in many different ways．The most common way is by talking with others．Besides talking，we can also use body language．When we use body language，we need to use body to show what we mean．Sign language is a kind of body language．Let’s see more about it．

  Sign language is popular among dumb people who are unable to speak or don’t want to speak．If you want to communicate with a foreigner，but you can’t speak his language and he can’t speak Chinese，what can you do?Maybe you can communicate by making signs．Now let’s learn some signs Indians often use．

    *When they are hungry，they move their right hands back and forth in front of their stomachs．

    *When they mean“Let’s eat”．they put their right hands and move them up and down in front of their mouths．

    *When they have had enough，they part their thumbs and first fingers,and move their hands from their chests to chins．

    *If they have a stomachache，they put both hands on their stomachs，and move them back and forth．