Look carefully at the back of a California state quarter. A man with a walking stick is pictured there. A bird called a California condor(大秃鹫)is flying overhead. Who is this man, and why is he so important that he is featured(处于显著地位)on the back of a coin?
      The man on this quarter is John Muir. Even as a child, Muir loved watching nature. As a young man, he spent much of his life exploring the beauty of the wilderness. He walked more than a thousand miles across the country, through fields and woods. John Muir liked writing about the places he visited, describing their beauty.
       Muir also wrote about problems. In order to create more farmland for sheep and cattle, many trees were being cut down. This made Muir unhappy and worried, because he knew that trees were important to forests and to the animals that lived in them．Muir believed that nature should be conserved(保护)instead of being changed by human beings. He wrote articles in magazines and newspapers to spread the word about conserving forests. Soon, others began to listen.
       Muir wrote letters to important people, such as President Theodore Roosevelt. The president admired Muir’s love for nature. When Roosevelt came to visit Muir in California. Muir convinced(说服)the president to go camping with him for three nights under the trees so they could talk about conservation. Later, President Roosevelt set aside 148 million acres of land for national forests and established(建立)five national parks. National parks are large areas of land that are protected from development. This means that people cannot build homes or businesses there. One of these parks is Yosemite National Park, the area that is featured on the back of the California quarter.
     Though it has been almost one hundred years since John Muir died, people continue his work today. His work as a conservationist helped us to see the beauty of our natural world. John Muir made us understand the importance of protecting our earth and our resources---then, now, and for the future.

如图所示，直线A为电源的U-I图线，曲线B为灯泡电阻的U-I图线，用该电源和小灯泡组成闭合电路时，电源的输出功率和电路的总功率分别是(     )

阅读下面的文字，完成下列小题。

《红楼梦》的开篇神话

    《红楼梦》是由一个神话故事开端的。说的是大荒山无稽崖下，有一块女娲补天时未被采用的石头，幻化为神瑛侍者，每天用甘露浇灌三生石畔上的一颗绛珠仙草，后来仙草修成女身，愿把一生所有的眼泪还他的情。因此一事，便引出一部悲金悼玉的《红楼梦》来。

    故事虽然说来荒唐无稽，但是任何神话都有其尘根俗缘。曹雪芹编造的这个神话故事，毫无疑问也是有其现实的基础的。那么，《红楼梦》中的这块顽石，到底生于何方何地呢？作者说是本于“大荒山，无稽崖”，用脂砚斋的话来说，就是“荒唐也，无稽也”，亦即是无可稽考之处。在我看来，这是作者和批者有意让人处于扑朔迷离之中，它应当是真有其处的。依据相关材料揆情度理，我认为，它应当是我国东北部的长白山。在远古时代，人们便称此为“大荒山”。我国第一部地理学著作《山海经》中记载：“大荒之中有山，名不咸，在肃慎之国。”肃慎，位于我国东北的东北部；不咸，蒙语即神仙的意思；不咸山，即仙山。长白山天池之畔有一天豁峰，山峰形状奇特。山石巨大，其中最大的一块，便名曰“补天石”。

    “绛珠仙草”又是什么呢？我认为，它即是长白山上的名贵特产人参。人参常被称为“神草”或“仙草”，长着对生的绿叶，绿叶中间挺立着一株长长的花柱，柱上结着一串串红宝石似的珠果，颜色绛红绚丽，形状如同南国红豆，晶莹剔透。这样看来，这个“绛珠仙草”不是人参又是什么呢？

    “神瑛侍者”呢？他似是“神鹰”的谐音。很早以前，满人中间流传一个神话：有三个仙女在长白山天池里洗澡，有一只神鸟（也有称说神鹰的）噙来一颗绛红的仙果放到最小的仙女佛库伦的衣服上，仙女吞下红果后生个男孩，便是清世祖先布库里雍顺。因此，神鸟（或神鹰）与绛红朱果的兰因絮果，恩恩怨怨，早就缔结在三生石畔了，曹雪芹只不过是将其巧妙地改造了一番，且完全不露一点痕迹。

    为什么曹雪芹要用这么一个神话故事，来牵引出这部百年望族的兴衰史呢？曹雪芹先人早在明万历年间迁居沈阳附近，加入旗军正白旗。他们为清室开创基业，屡立卓越功勋。因此曹雪芹用这么一个神话故事开篇，这与他绵绵不绝的寻根怀旧思恋有着直接的关系。曹雪芹生于末世，当年随同清室一同入关的八旗子弟，个个都是声名显赫，唯独他结庐在荒凉的西郊荒野村，穷困潦倒，怎能不产生“娲皇只用了三万六千五百块、单单剩下一块未用”的慨叹呢？

    曹雪芹在一首《画中诗》中说：“爱此一拳石，玲珑出自然。溯源应太古，堕世又何年？有志归完璞，无才去补天。不求邀众赏，潇洒做顽仙。”这里明明点出这块顽石的来历，它的根源本来尊贵，详溯其源当是出自太古的大荒山（即长白山）山巅，遥想当年是何等的荣耀，只是今日才蒙蔽尘埃，埋没于蓬蒿之中。现虽欲返璞归真，但又不能去攀结那些豪门权贵，只能是“自怨自愧，日夜悲哀”而已！并于万般无奈之中，才求诸笔墨文字，冀图得到诸如空空道人之类的人去传述其一番历历可数的心迹罢了。