题干

假定当A商品的互补品价格上升10%时,A商品需求变动量为20单位;当A商品的替代品价格下降10%时,A商品需求变动量为30单位。如果其他条件不变,当A商品的互补品价格上升10%、替代品价格下降10%同时出现时,那么,A商品的需求数量                                                               

A:增加50单位

B:减少50单位

C:增加10单位

D:减少10单位

上一题 下一题 0.0难度 选择题 更新时间:2020-02-13 05:20:42

答案(点此获取答案解析)

B

同类题1

   It's not easy to be an astronaut's son. Everybody expects(期望) you to be special or perfect. I often wonder how my father ever had a son like me. I mean he's so special and so good at everything he does. Even in middle school he was class president and captain of the football team. Well, to be honest, I often dream about being some kind of hero or doing something special-like saving a child from a burning building or discovering a new star. I was daydreaming at school one morning when my teacher said there would be a Father's Day writing competition for the whole school "I hope we have a winner right here in my class."
   When I got home, I started to think about what to write. My father is an astronaut. No, I wouldn't start like that. That was the way others saw him. How did I see my father? Hmm. I saw him sitting with me in the dark when I had a terrible dream. I remembered how he hugged me for hours when my dog Spotty was killed by a car. Yes, these were the things I was going to write. To me, he wasn't just a world-famous astronaut. He was my dad.
   My parents and l went to school Thursday night. There were so many people in the big hall! My dad looked at me, and I shrugged(耸肩).
   The third prize was announced(宣布) and it was not me. I was relieved(释然)and disappointed at the same time. The second prize was announced. It was me. I went up to the stage and read what I had written, "My father's son". When I finished,the people stood up and cheered. I saw my father blowing his nose. Tears were running down my mother's face. Dad cleared his throat and put his hand on my shoulder. "Son, this is the proudest moment of my life.''
   It was the proudest moment of my life, too. Maybe I'll never be a great hero or win a Nobel Prize, but it was enough just to be my father's son.