我国西北地区大多为（　　）

如图，Rt△APC的顶点A，P在反比例函数y＝$\frac{1}{x}$的图象上，已知P的坐标为（1，1），tanA=$\frac{1}{n}$（n≥2的自然数）；当n=2，3，4…2010时，A的横坐标相应为a₂，a₃，a₄，…，a₂₀₁₀，则$\frac{1}{a_2}$+$\frac{1}{a_3}$+$\frac{1}{a_4}$+…+$\frac{1}{a_{2010}}$=（　)

因素：A．液体的温度．B．液体的表面积．C．液体表面的空气流动速度．

校验：

B

    A boy and his father walk in the mountains. Suddenly the boy falls, hurts himself, and cries, "AAAhhhhhhhh!!!" To his surprise, he hears the voice(声音) repeating(重复), somewhere in the mountain, "AAAhhhhhhhh!!!" Then the boy cries again, "Who are you?" He hears the answer "Who are you?" He thinks someone else in the mountain is laughing at him, so he gets angry and shouts "Foolish!" He receives the answer "Foolish!"

    He looks at his father and asks, "What's going on?" The father smiles and says, "My son, listen." And then he shouts to the mountain, "I love you!" The voice answers, "I love you!" Again the man cries, "You're the best!" The voice answers, "You're the best!"

    The boy is surprised, but does not understand. Then the father explains(解释), "People call this 'Echo', but really this is life. It gives you back everything you say or do. Our life is just a reflection（反映）of what we have done. If you want more love in the world, have more love in your heart. If you want to be successful(成功), work hard. This can be used in everything in life. Life will give you back everything you have given to it."