根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    One day, a farmer took a bag of wheat to town. He didn't know what 1 when the bag fell off his horse. The bag was 2 heavy for him to lift. He hoped that 3 would come and help him.

    Before long a man came over. But the farmer was 4 when he saw the man, because he was the famous judge(法官) in "town. The farmer was afraid to ask him for 5.

    As soon as he came up to the farmer, the judge 6 his horse and said," You need my help, don't you? Let me help you." Then he took one end of the bag, and the farmer took 7. They 8 the bag of wheat onto the horse.

    "Sir," asked the farmer, "how can I 9 you?"

    "Well," the judge replied, " 10 you see anyone in need of help, do the same for him."

若a＞1，b＜0，且a^b+a^﹣b=2$\sqrt{2}$，则a^b﹣a^﹣b的值等于（　　）

一个圆锥体底面积不变，高扩大2倍，体积也扩大2倍．

方程是等式．