一警车以的速度在静止的空气中追赶一辆速度的汽车，若警车警笛声的频率为800Hz，空气中声速u=330m/s，则客车上人听到的警笛声波的频率是（）Hz。

A、710

B、777

C、905

D、826

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•  丹麦首都哥本哈根。凌晨2时15分。 
   当班的见习消防队员拉斯马森拿起突然铃声大作的电话，一阵微弱的喘息声传来：“我摔倒了，救命啊……”声音像一位老夫人，在确定不是恶作剧后，拉斯马森询问道：“请把您公寓的地址告诉我！” 
   “我……想不起来了。” 
   “那请把您的名字告诉我！” 
   “我不记得了。” 
   “请您不要把电话挂断，我们好通过电信局找到您的住处！”拉斯马森想到了电信局，他马上与电信局取得了联系。可值班人员却表示，现在人员不齐，要查清电话是从哪里打来的，根本做不到……无计可施的拉斯马森叫醒了中尉，中尉拿起了电话：“夫人！……夫 人！能告诉我床前地毯旁边是什么吗？”“是镶木地板，老式的打蜡地板。“天花板高吗？” “高……我觉得很高……”“这么说，您住的是老式房子！百叶窗关着没有？”“没有。”中尉兴奋地对拉斯马森说道：“寻找一幢窗户狭长的老式房子，房子的窗口有灯光，大约在二三层......”中尉又对着话筒问道：“夫人，能告诉我，您住的街道的名称吗？”
   然而，话筒里再没有人搭腔了。中尉知道，老太太大概昏过去了，没有把电话挂上。
   时间一分一秒地流逝着，每一秒钟每一分钟都变得漫长起来，室内挂钟的滴答声越来越响，每一次的滴答声都像小锤子般敲在几个人的心上。 
   一个小时过去了，老夫人仍无反应。焦灼和冷汗悄悄地爬上了几个人的面孔、心头……拉斯马森对中尉说道：“我有个主意……”他的主意立即被采纳。 
   凌晨3时30分，14辆轻便消防车同时出动，开往依然沉睡着的城市的各个街区，警笛的尖啸声撕碎了夜的宁静。指挥部里拉斯马森把电话听筒紧紧地贴在一只耳朵上，把耳机扣在另一只耳朵上。整个哥本哈根城都被惊动了，家家户户灯火通明……拉斯马森突然叫道：“中尉，我听见了！我听见警笛声了！消防车大概就在离老夫人家不远的街上！”中尉用手中的对讲机命令道：“1号车，停止鸣笛！”拉斯马森对中尉说道：“我还听得见。” “12号车，停止鸣笛13号车，停止鸣笛！……6号车，停止鸣笛！……12号车，停止鸣笛！”拉斯马森惊叫道：“就是这里！” 
   “12号车，我是指挥部，就在你们那个地段，用扩音器说明一下理由。让这条街上所有的灯光都熄灭，最后亮着灯的一定是老夫人的家！” 
   5分钟后，12号车所在街区的窗口黑了下来，只剩下一扇窗口还亮着。稍后，拉斯马森在电话里听到了撞破房门的声响，继而是一位消防队员的声音：“喂！指挥部吗？我们已到现场，老夫人昏迷了，颅骨有伤，大概是床头磕的，脉搏有轻微跳动……” 
   太阳升起来的时候，消防队不断有电话打进来，询问老夫人的情况。当获悉这位72岁的老人因为抢救及时，已经在医院苏醒过来时，人们纷纷表示，那个凌晨，响彻哥本哈根的消防车的尖啸声，是他们听过的所有声音中最动听的声音。 
  1．本文所写的故事发生于凌晨2时15分的哥本哈根，起因是 ，经过是 ，结果是老夫人顺利获救。（每处不得超过16字） 
  2．请为本文拟一个恰当的题目。（8个字以内）
   
  3．从拉斯马森、中尉与老夫人的通话中，可以看出消防队员 的品质。
  4．“指挥部里拉斯马森把电话听筒紧紧地贴在一只耳朵上，一句与上文的哪句话呼应？
   
  5．文中画线句子为什么不直接引用中尉下达的“12号车，停止鸣笛”的命令，而是不厌其烦地从1号车说起？
   
  6．下面两句话写得很好，说说好在哪里。 
   （1)每一次的滴答声都像小锤子般敲在几个人的心上。 
   
   （2)警笛的尖啸声撕碎了夜的宁静。
   
  7．对于本文叙述的故事，你有什么感受？请写在下面。（含标点60字以内）
   

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• Some of the most popular attractions across America are the many free concerts offered to public throughout the year. These involve not only amateur performers, but professional artists as well. The public parks of many cities across the country usually have bandstands and large lawns. As a service to citizens, they rent out space to performers free of charge. Amateur groups, with nothing more than a desire to perform. offer their talents freely to public. Semi-professional artists are pleased to get the chance to perform. before the public to perfect their craft and nurture the hope of being discovered before beginning a professional career. Famous professionals also give free concerts to make contact with their admiring fans. Often such concerts are sponsored by a large corporate organization and offered to the public free of charge as a cultural service and support for the arts.
  The free concerts feature all kinds of music from rock and roll, jazz, country, western to the classics. In addition, free performances may include the plays of Shakespeare or experimental theatre of modern dramatists. In New York's Central Park there has long been a summer Shakespeare festival which draws huge crowds to the free performances.
  Of these concerts the ones held on a summer evening in the park are the most popular. They take on a festive air. Friends and groups gather together after work and spread out a blanket on the lawn facing the performers' stage. The early comers get the best locations and enjoy a picnic supper while it is still daylight. The free seating is on a first come basis. Therefore, by the time the concert begins, as many as five thousand or more people may be in attendance. The concerts usually begin at 8 p. m and are performed under the stars. The sound is made sufficiently loud so that no matter where one chooses to sit, he can hear very well. The only disturbance may be the sound of an overhead airplane on its final approach to an airport or the far-off siren（警笛声) of an ambulance on its way to the hospital. This matters little! What counts is to soak up the atmosphere created by the music and to be with friends in the fresh open air. The best part of it all is that it's free!
  Many American parks give free concerts on their lawns because they______.
  A．have the necessary facilities
  B．call attract more visitors
  C．want to serve the public
  D．are in a position to invite musicians

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• 当您听到警笛声并且看到一辆有闪烁的红色紧急讯号灯的救急车辆离您很近地行驶来，您必须（）。

  A、将车开到路的右侧边缘并停下

  B、将车驶入右边车道并缓慢行驶，直到该车经过

  C、加速行驶使交通通畅

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• “SOS”是世界通用的紧急求救讯号，它的由来是()

  A、“紧急求救”英文单词的第一个字母。

  B、在无线电通讯上摩尔斯电码“紧急求救”代号所代表的三个字母。

  C、警笛声的长短。

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• 一警车以υS=30m/s的速度在静止的空气中追赶一辆速度υR=20m/s的轿车，若警车警笛声的频率为800Hz，空气声速为u=330m/s，则轿车上人听到的警笛声波的频率是（)Hz。
  A．827
  B．777
  C．906
  D．859

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