阅读D：
　　“I can’t concentrate.”“My mind wanders when I try to study.”Lack of concentration is one of the most common complaints heard at school.
　　We all have the ability to concentrate.Think of the times when you were attracted to a super novel or the times when you were playing your guitar or piano.But at other times your mind races from one thing to another.Here are some tips.
　　Rest from time to time.Remember to take short breaks.Lectures are usually 50 minutes long,and that’s about the length of time most people can direct their attention to one task.But that’s just an average.Your concentration time might be shorter(20-35 minutes)or longer(perhaps 90 minutes).When you take a break,you get more oxygen to your brain!When we sit for long periods,blood tends to be pooled in our lower body and legs.Get up and walk around the room for a couple of minutes.As a result,more oxygen is carried to the brain and you can concentrate better.
　　___If you study one subject for a long time,you may find it hard to concentrate.Many students improve their concentration by changing one subject to another every one to two hours.In this way you can pay more attention to something that’s different.
　　Reward yourself.Give yourself a reward when you’ve completed a task.The task might be small,such as staying with a difficult paper until you’ve finished.But giving yourself a reward can help you be more interested in doing other tasks.
　　Increase your activity level.Your concentration wanders more easily if you just read an article straight through.Instead,take the heading for each part and turn it into a question.For this part,that would be,“How can I increase my activity level while studying?”Then study that part to answer that question.Do this routinely.The questions give us a focus for each part and increase our involvement(参与).
　　小题1:According to Paragraph 3,what’s the purpose of walking around?
　　A.To help us stay fit.
　　B.To benefit our lower body.
　　C.To provide the brain with more oxygen.
　　D.To increase our concentration time to 90 minutes.
　　参考答案：C
　　参考解析：根据第三段的句子：Get up and walk around the room for a couple of minutes.As a result,more oxygen is carried to the brain and you can concentrate better.可知四处走动的目的是提供大脑更多的氧气，所以选C。
　　小题2:What’s the best title for Paragraph 4?
　　A.Study for one hour each time.
　　B.Do something difficult.
　　C.Study in different ways.
　　D.Change subjects.
　　参考答案：D
　　参考解析：根据第四段的句子：If you study one subject for a long time,you may find it hard to concentrate.Many students improve their concentration by changing one subject to another every one to two hours.可知这段讲的是改变科目，所以选D。
　　小题3:In the last paragraph,the writer suggests that______.
　　A.we just read the heading of some articles
　　B.we do our best to read an article straight through
　　C.we ask ourselves questions about what we are reading
　　D.we ask other people questions about the article we are reading
　　参考答案：C
　　参考解析：根据最后一段的句子：Instead,take the heading for each part and turn it into a question.可知作者建议我们就自己阅读的东西问自己一些问题，所以选C。
　　小题4:The writer wrote the passage to______.
　　A.encourage us to try to concentrate
　　B.teach us how to concentrate while studying
　　C.give us the reasons for a lack of concentration
　　D.list the benefits we can get from concentration
　　参考答案：B
　　参考解析：根据第一段的句子：But at other times your mind races from one thing to another.Here are some tips.可知这篇文章是告诉我们在学习的时候怎么集中注意力。选B。
　　参考译文：
　　“我不能集中注意力。”“当我试图学习的时候，我的脑子在转来转去。”注意力不集中是学校里听到的最常见的抱怨之一。
　　我们都有集中注意力的能力。想想你被超级小说吸引的时候，或者你弹吉他或钢琴的时候。但有时你的思维会从一件事跑到另一件事上。这里有一些提示。
　　不时休息。记得休息一下。讲课通常有50分钟长，这是大多数人将注意力集中在一项任务上的时间长度。但这只是一个平均值。你的集中时间可能更短（20-35分钟）或更长（90分钟）。当你休息时，你的大脑会得到更多的氧气！当我们长时间坐着的时候，血液往往会聚集在我们的下半身和腿上。起来在房间里走走几分钟。结果，更多的氧气被输送到大脑，你可以更好地集中精力。
　　如果你长时间学习一个科目，你会发现很难集中注意力。许多学生每隔一到两个小时就把一门课改成另一门课，以此来提高注意力。这样你就可以更多地关注一些不同的东西。
　　奖励自己。完成任务后给自己奖励。这项任务可能很小，比如在你完成之前一直呆在一张困难的纸上。但是给自己一个奖励可以帮助你对完成其他任务更感兴趣。
　　提高你的活动水平。如果你只是直接读一篇文章，你的注意力会更容易分散。相反，把每个部分的标题变成一个问题。在这一部分中，我会说，“我怎样才能在学习时提高我的活动水平呢？“然后研究这个部分来回答这个问题。经常这样做。这些问题给了我们每个部分一个重点，并增加了我们的参与。