阅读理解
    James is a good student and he has lots of friends，but he also has a problem. Some older boys are bullying(欺负)him at school. James is very unhappy and he doesn't know what to do about it. Here are some suggestions to him and other teenagers in this situation.
    Don't feel worried. It's not your fault(过错)! Being bullied can make you feel very lonely and angry，but you are not alone. Don't feel that you have to hide the problem. You should find a person you can trust，and tell them. It might be your teacher，your parents，or even your friend's parents. After you tell someone，you will get some support and feel some relief(解脱).
    Speaking to an adult might make you nervous，but here are other things you can do. Some people express their feelings more easily on paper. Write a letter to someone or keep a diary. Include all the details(细节)about what the bullies do, as well as when and where the bullying happens. You can use it as proof to show what is going on. And it is a wonderful idea to show your letter or diary to a teacher or another responsible adult. Then the bullies will feel very afraid if their names appear in a letter!
    Also，don't show you are sad and don't try and fight with the bullies. You could get in trouble yourself. Ignore them and just walk away. The bullies will soon stop.

下列各句中标点符号使用正确的一项是（　 　）

                                                            

材料一：“轮椅叫我三分矮，我叫人生步步高。”张海迪这么说了，也这么做了。为了学习英语，她在墙上、桌上、镜子上、胳膊上都贴上单词纸条，每天不背会10个单词不睡觉。后来她翻译了英文长篇小说《海边诊所》等书。   

材料二：列夫·托尔斯泰青年时期一度沉湎于奢华和挥霍，荒废了学业，还留过级。后来他醒悟过来，决心同软弱做斗争，并为自己制定了《发展意志守则》。他坚持每天记日记，并重读以前的日记，用来进行自我监督；强迫自己完成每天该完成的工作，终于锻炼出坚强的意志。

请结合材料回答：

圆柱的侧面积等于（   ）乘以高。