A young man was about to finish school. For a long time he had1to get a beautiful sports car. He knew his father could well 2it, so he told him that a sports car was all he wanted.
Then on the morning of his graduation（毕业）,he was called to his father’s room. His father told him how 3he was to have such a fine son, and told him how4he loved him. He handed his son a beautiful gift box.5, the young man opened the box and found a lovely Bible（圣经）with his name on it. Angrily, he raised his6to his father and said, "With all your money you give me a Bible? " He then7out of the house, leaving the Bible.
Many years passed and the young man was very 8in business, and had a beautiful home and a wonderful family. 9that his father was very old, he thought perhaps he should go to see him. He had not seen him 10that graduation day. Before he could go, he received a 11telling him that his father had died. He had to go home immediately and take12of the things that his father left him.
When he began to search through his father’s important papers, he saw the still new Bible, 13as he had left it years ago. He opened the Bible and began to14the pages. As he was reading, a car key with a tag（标牌）dropped from the back of the Bible. On the tag was the15of his graduation, and the words "PAID IN FULL". Sadness and regret（悔恨）filled his heart.
上是单调函数，则有 （ ）
