武后时，官员张衡在市场购买食品受到御史的弹劾。唐德宗时，宰相刘宴入朝时在路旁购买胡饼吃，群僚对此豪不奇怪。这反映出唐朝（    ）

求1+2+2²+2³+…+2²⁰¹²的值，可令S=1+2+2²+2³+…+2²⁰¹²，则2S=2+2²+2³+2⁴+…+2²⁰¹³，因此2S﹣S=2²⁰¹³﹣1．仿照以上推理，计算出1+5+5²+5³+…+5²⁰¹²的值为（　　）

A．   B．  C．      D．

    Hello, I'm Jack. I live in a house. My address is 246 Second Street. It's far from the school. So I go to school by bus every day. But my house is near the park. So I often go to the park on foot. Tom is my friend. He lives in a house, too. It is near the school. So he goes to school on foot every day.