"Can I see my baby?" the happy new mother asked. When the baby was lying in her arms and she moved the cloth to look upon his tiny face, she gasped(吃力地喘着气). The doctor turned quickly and looked out of the hospital window. The baby had been born without ears. Luckily, time proved that the baby's hearing was perfect. Though the misfortune(不幸)happened to him, he grew into a handsome boy. Yet he felt ashamed when he communicated with others.
"You should get in touch with other young people," his mother told him, with a kindness in her heart. The boy's father talked with the family doctor about his ears. "Could nothing be done?"the father asked. "I believe I could give him a pair of outer ears, if they could be got," the doctor replied.
Two years went by. One day, his father said to the son, "You are going to the hospital, Son. Mother and I have someone who will donate the ears you need, but it's a secret."The operation is a big success. Later he married and entered the diplomatic(外交的) service. One day, he asked his father, "Who gave the ears? Who gave me so much? I could never do enough for him or her."
"You could, my son," said the father, "but the agreement was that you are not to know…not yet."
The years kept their secret, but one of the darkest days did come. He stood with his father over his mother's casket(棺材). Slowly, the father stretched forth(伸出) a hand and raised the thick, reddish brown hair to reveal the mother had no outer ears.
"Mother said she was glad she never let her hair be cut," his father whispered gently, "and nobody ever thought mother less beautiful, did they?"
（其中
）所表示的圆锥曲线（椭圆、双曲线、抛物线）方程中任取一个，则此方程是焦点在
轴上的双曲线方程的概率为
