阅读理解
    American country music is also known as(被称为)country Western music．It has a very long history．It comes from the folk songs of immigrants(移民)from Britain．
    Country music uses simple music and words to express everyday feelings such as loneliness，love，and sadness．That is to say，country music describes life．It talks about friends and enemies，trucks and roads，farms and crops．People in many parts of the world like country music，because everyone can understand what the music is about．
    Country Western music became popular first among cowboys(牛仔)in the American West courttryside．Cowboys had to take care of cows day and night．When they were alone with the cows，they often sang beautiful and peaceful songs to calm the animals and to overcome their own fear．They were not well—educated and so they sang about their daily life in very simpie words．They played guitars，violins，and other instruments．  In the south of America，many people added instruments from their homes，like bottles and spoons．  When cowboys visited their friends and families on holidays like Thanksgiving，they usually sang and played country Western music．
    In recent years，many musicians have made country Western music a little different from the one in the past．These changes make the songs sound even better．Today singers such as Garth Brooks， Reba McEntire，Emmylou Harris，Lyle Lovett，Eddie Rabbitt，LeAnn Rimes，Randy Travis，and a group called Alabama are singing and playing in different styles．They have brought country Western music more and more fans from all over the world．

二次函数y=ax²+bx+c的图象如图所示，则一次函数y=bx+b²﹣4ac与反比例函数y= $\frac{a+b+c}{x}$ 在同一坐标系内的图象大致为（   ）

雷达使用的电磁波是（    ）

博物馆近代展馆前，导游小王向同学们解说关于近代列强是如何一步步侵略中国，不断地侵占中国权益时是这么说的：“起初允许在通商口岸开设工厂①”；接下来开放广州、厦门等为通商口岸②；后来各国派兵保护东交民巷使馆界，界内不许中国人居住③；最后还趁机割占我国北方领土达150万平方千米 ④。”显然小王把史实的顺序弄错了，那么正确的顺序是（    ）

如图所示，与传送带等高的光滑水平台上有一小物块以某一初速度滑上传送带．若传送带静止时，物块离开传送带后落在地上P点，若传送带顺时针匀速转动时，则物块将落在（  ）