Michael and Dick are good friends, but they like to play jokes on each other. One holiday, they decided to go to London together. They went to the station and bought their tickets.
Michael got on the train first. He dropped his ticket on the platform when he got into the carriage. Dick, who was close behind, saw the ticket fall and quickly picked it up. He put it in his pocket, but didn't tell Michael. After they had been in the train for a while, they heard the conductor coming down the corridor, shouting, “Tickets, please!” Michael looked for his ticket and of course couldn't find it.
“Oh dear, I can't find my ticket, Dick,” Michael said.
“Look for it carefully, Michael; it must be somewhere.” said Dick.
“No, I can't find it anywhere. What shall I do?” said Michael.
“Perhaps you'd better hide under the seat; then the conductor won't know you are here.” So Michael hid under the seat. At this time, the conductor came in. “Tickets, please,” he said. Dick handed him tow tickets and said, “This is mine. The other is my friend's. But he prefers to stay under the seat.”
两点分别对应实数 
，则下列结论正确的是（ ）