题干

如图甲所示的电路中,R0是标有“6V 6W”字样的元件(阻值不变),R是滑动变阻器,通过小灯泡L的电流随其两端电压变化的图象如图乙所示.闭合开关S,滑动变阻器的滑片P滑到最左端时,R0恰好正常工作.

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    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.