把一个圆柱削成一个最大的圆锥，削去部分的体积是这个圆柱体积的（　　）

阅读下面的文字．完成小题

    吴良，定远人。初名国兴，赐名良。与弟祯俱以勇略闻。从太祖起濠梁，并为帐前先锋。良能没水侦探，祯每易服为间谍。张士诚兵据秦望山，良攻夺之，遂克江阴。即命为指挥使守之。

    时士诚全据吴，跨淮东、浙西，兵食足。江阴当其要冲，枕大江，扼南北襟喉，士诚数以金帛啖将士，窥衅。太祖谕良曰：“江阴，我东南屏蔽，汝约束士卒，毋外交，毋纳逋逃，毋贪小利，毋与争锋，惟保境安民而已。”良奉命惟谨，备御修饬。以败敌功，进枢密院判官。士诚大举兵来寇，艨艟蔽江，其将苏同佥驻君山，指画进兵。良遣弟祯出北门与战，而潜遣元帅王子明帅壮士驰出南门。合击，大败之，俘斩甚众。敌宵遁。寻复寇常州，良遣兵从间道歼其援兵于无锡。当是时，太祖数自将争江、楚上流，与陈友谅角，大军屡出，金陵空虚。士诚不敢北出侵尺寸地，以良在江阴为屏蔽也。

    良仁恕俭约，声色货利无所好。夜宿城楼，枕戈达旦。训将练兵，常如寇至。暇则延儒生讲论经史，兴学宫，立社学。大开屯田，均徭省赋。在境十年，封疆宴然。太祖常召良劳曰：“吴院判保障一方，我无东顾忧，功甚大，车马珠玉不足旌其劳。”命学士宋濂等为诗文美之，仍遣还镇。寻大发兵取淮东，克泰州。士诚兵复出马驮沙侵镇江巨舰数百溯江而上良戒严以待太祖亲督大军御之士诚兵遁追至浮子门良出兵夹击获卒二千。太祖诣江阴劳军，周巡壁垒，叹曰：“良，今之吴起也！”洪武三年进都督同知，封江阴侯，食禄千五百石，予世券。

    四年讨靖州、绥宁诸蛮。五年，广西蛮叛，副征南将军邓愈帅平章李伯升出靖州讨之。数月，尽平左右两江及五溪之地，移兵入铜鼓、五开，收潭溪，开太平，歼清洞、崖山之众于铜关铁寨。诸蛮皆震慑，内附，粤西遂平。十二年，齐王封青州。王妃，良女也，遂命良往建王府。十四年卒于青，年五十八。赠江因公，谥襄烈。

（选自《明史列传第十八》）

学完隋唐历史之后，四位同学作了主题演讲，你认为能准确地概括这段历史的基本特征的是（     ）

阅读下列短文,从每小题所给的A、B、C、D四个选项中选出一个最佳选项。

    Answers to life can be found in everyday events. Watching nature, watching people and watching animals communicate with each other provide some of the simplest ways to life's biggest problems.

    This became clearer to me yesterday. It caused me to ask myself, “How do I respond (反应) to the storms in life?”

    People usually run when it starts to rain. I love to walk in it, stand on my front door and feel it. I grew up doing it and have never really felt the fear many people do.

    The animal world senses changes in the weather far earlier than humans. My dog, Ricky, begins to shake long before the storm is close enough to be noticed. I was about to feed my three dogs yesterday and as usual, I let them out in the yard first. They didn't move when thunder came across the skies. So I placed their food in their bowls and called Ricky into the kitchen.

    Ricky was just standing there in place next to his bowl. The thunder became louder, which forced him to stop eating his meal. Then I watched Phil. He made his way across the kitchen floor and stood over Ricky's bowl. He ate all the remaining food. Generally, if Ricky was standing there, he wouldn't dare (敢) come close. But today, he took advantage (优势) of the storm and got what he wanted. His hope for the prize outweighed (胜过) his fear of the storm.

    That's when it hit me. As men, we face all kinds of storms. They come in unannounced. Sometimes we stay in a corner or under the blankets, hoping it will all pass. However, if you dare put your head out, you'll discover there're people doing what they must to get what they must have out of life. Isn't it time you decided to take advantage of the storm?