题干

“冬眠山药”是山东省单县农民为避开高峰上市,将本该秋末收获的山药,封上30公分厚的垄,使山药在土下“冬眠”,开春后再将山药挖出上市,价格比秋末翻了一翻。“冬眠山药”表明
①商品价格影响市场的供求
②山药冬眠前后的价值是完全一样的
③市场供求影响商品的价格
④农业生产要不断提高自身的经济效益

A:①②③

B:①③④

C:①②④

D:②③④

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答案(点此获取答案解析)

B

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    Jonathan Cranwell sat on a hard bench behind the long narrow desk and watched the flies fly lazily in the sun. The drone of the younger boys reading letters and the older boys reciting Latin verbs made him sleepy. Jonathan had to force his eyes to stay open. He wanted to learn something new!

    He looked up at the schoolmaster's high desk in the front of the room. The new teacher was from Harvard College. Jonathan's father had been impressed with him. The boys had already had several other teachers, but none of them seemed to inspire Jonathan. So far, there was nothing to show that this one was special , though he'd only been there two days.

    “It's too hot to sit and memorize lessons,” the schoolmaster said. “We'll move outdoors for the next part of our lesson.” He led the group of boys into the schoolyard. “You younger boys, dig for grubs and beetles ( 幼虫和甲虫). Count their feet. See if you can describe their shells”

    Jonathan watched the teacher surrounded by laughing young students. No one had ever used the schoolyard itself for a classroom. “What next ?” he thought. He didn't have time to think about the younger boys, for he was running after butterflies and dragonflies himself.

    Jonathan and his friends liked this new way of learning.

    “It will be a clear night tonight. Go outside and look at the sky,” said the schoolmaster. “Look at the stars and notice their brightness and the patterns they make. These patterns have names from Greek mythology(神话), names like Orion, Aries, and others. Tomorrow we will learn about the ancient stories on them.”

    “How is the new schoolmaster ?” asked Jonathan's father that evening, when Jonathan announced he was going out to look at the sky.

    “He's different from any other schoolmaster we've had,” Jonathan admitted. “He seems interested in everything around him, and he wants us to be curious too. He even used the schoolyard as a classroom!”

    “So Mr. John Adams and his new ways make school useful to you after all,” joked Jonathan's father.

    “I believe he has,” said Jonathan. “I know I won't forget the lessons he has taught us!”