请用计算器求数据271，315，263，289，300，277，286，293，297，280的平均数，结果是____ 

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陈谏议教子

    太尉^①陈尧咨为翰林学士^②日，有恶马，不可驭，蹄啮伤人多矣。一日，父谏议^③入厩，不见是马，因诘^④圉人^⑤，乃曰：“内翰^⑥卖之商人矣。”谏议遽^⑦谓翰林曰：“汝为贵臣，左右尚不能制，旅人安能蓄此?是移祸于人也。”亟^⑧命取马，而偿其直，诫终老养焉。

【注释】①太尉：一种高级官衔。②翰林学士：官职名称，皇帝顾问。③父谏议：担任濂议大夫官职的父亲。④诘：质问，责问。⑤罔人：养马的人，⑥内翰：此指陈尧咨。⑦遽：急忙。⑧巫：急迫地。

      If you want to be a better reader，what should you know about the speed(速度)of reading? Some people read very quickly，when others read very slowly. But which one is better? The quick reader may be a good reader when he reads a story-book for fun. But he may not be able to slow down to read instructions(说明书) carefully. The slow reader may be a good reader. But he may spend too much time reading a story for fun. So the reader who reads everything quickly or the one who reads everything slowly isn't really a good reader. Here are four things to remember about the speed of reading.
       Knowing why you are reading will help you to know whether(是否) to read quickly or slowly.
Some things should be read slowly throughout. Examples(例子)are instructions for making or doing something. Math books，science and story-books are full of important information. You must read these things slowly to understand and remember every important idea.
     Some things should be read quickly throughout. Examples are stories for enjoyment，letters from friends，and some news from newspapers.
In some of your reading，you must change your speed from fast to slow and slow to fast. You will need to read some pages quickly and then slow down and do more careful reading when you come to important ideas.

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春望

杜甫

国破山河在，城春草木深。

感时花溅泪，恨别鸟惊心。

烽火连三月，家书抵万金。

白头搔更短，浑欲不胜簪。