题目

I often hear some students say English is difficult, and it gives them a headache. So they can’t learn it well. But English is very easy for me. I’ m good at it. I’m very glad to tell you something about how I study English.First, I think an interest in English is very important. When I was in Grade One，we had a new subject-English. It was fresh for me. I was interested in it, so I worked hard at it. Soon we had an English exam and I got a very good mark. How happy I was! After that, I learned English harder and harder. Our English teacher often teaches us English songs, the songs soun为了解某学校学生一年中的课外阅读量，该校对800名学生采用随机抽样的方式进行了问卷调查，调查的结果分为四种情况：A、10本以下；B、10～15本；C、16～20本；D、20本以上．根据调查结果统计整理并制作了如图所示的两幅统计图表．各种情况人数统计频数分布表课外阅读情况ABCD频数20xy40（1）填空：x=________ ，y=________ ；（2）在扇形统计图中，C部分所对应的扇形的圆心角是________ 度；（3）根据抽样调查结果，请估计该校学生一年阅读课外书20本以上的学生人数________ ．