"Listen carefully to what I say," the time traveler said, "I shall tell you something that you will not agree."  

 "Why will we not agree?" I asked.

 "Because the science and mathematics you know are not correct,"  he said. "You believe there are only three dimensions(三维空间)-length, breadth(宽) and thickness." 

 "There is nothing to argue with that, " the youngest member of our little group said.

 "Exactly!"  the time traveler answered, "But there is also a fourth dimension - time."   

 "We all know about time, " another member of the group said. "Time passed."

 "I do not agree,"  the time traveler said, "Length, breadth and thickness do not pass. They stay in the same place in space.  We move about them. I can prove that time is the same. It does not pass. We move in time the same way that we move in breadth, length and thickness."

 None of us believed the time traveler, and we argued with him for many hours.

 "If we could travel back in time,"  the scientist said, "We could do things to change the future." 

 "If we could travel forward in time," the doctor(博士) said, "we could do things that change our present." 

 The time traveler smiled, "It is clear," he said, "that there is only one way I can show you that I am right. We must do an experiment. Please wait here." 

 He left the room and soon returned, carrying what looked like a clock.

 "This is a model of a time machine. It took me two years to make it," the time traveler said. "I want all of you to understand that when I start the machine, it will immediately travel in time and disappear from the present." 

 He turned to the youngest of all. "Give me your hand," he said.

 The young man put out his hand. The time traveler took it and placed it on the machine. Immediately, there was a sudden wind, and the little machine disappeared.

 I was certain this was not a trick, but the doctor was not so sure.

 "Are you asking us to believe," he said, "that the machine is now in a different time?" 

 "Certainly! In my laboratory, a full-size machine is almost complete. As soon as it is complete, I shall send myself on a journey through time. Would you like to see my machine?"

 "Are you serious about this?" the doctor asked.

 "I have never been more serious about anything," the time traveler said, "Come." 

We followed him to his laboratory. There, we saw the actual machine, not quite complete, but large enough for a man to sit in.

    Dick lived in England. One day in January he said to his wife, "I'm going to fly to New York next week because I've got some work there." "Where are you going to stay there?" his wife asked. "I don't know yet." Dick answered. "Please send me your address from there in a telegram (电报)," his wife said. "All right," Dick answered.

    He flew to New York on January 31st and found a nice hotel in the center of the city. He put his things in his room and then he sent his wife a telegram. He put the address of his hotel in it.

    In the evening he didn't have any work, so he went to a cinema. He came out at nine o'clock and said, "Now I'm going back to my hotel and have a nice dinner."

    He found a taxi and the driver said, "Where do you want to go?" But Dick didn't remember the name and address of his hotel.

    "Which hotel are my things in?" he said, "And what am I going to do tonight?" But the driver of the taxi did not know. So Dick got out and went into a post office. There he sent his wife another telegram, and in it he wrote, "Please send me my address at this post office."

    Birds live in trees. Squirrels(松鼠) live in trees. But do you know that some frogs（青蛙） live in trees, too?

    The tree frogs are hard to find. They can change color. On green leaves, they stay green. On a branch, they keep brown. Some tree frogs can change from green to gold or blue.

    Tree frogs have legs and wide feet. They have sticky pads (肉趾) at the end of their toes（脚趾）. These sticky toe pads keep the tree frogs from falling off.

    Tree frogs have different colors and markings on their skins(皮肤). Their eyes are different, too. Some have green eyes, some gray. Some frogs' eyes are gold, and some are bright red.

    The sounds they made in spring and summer are different, too. One frog makes a sound like a dog barking(狗叫). Another frog makes a loud noise like a snore（打呼噜）. There is even a frog that whistles（吹口哨）!

    I teach economics in a university three times per week. Last Monday, at the beginning of class, I asked my students how their weekend had been. One young man said that his weekend had not been so good. He had his wisdom teeth removed. Then he went on to ask me why I always seemed to be so cheerful.

    His question reminded me of something I'd read somewhere before: Every morning when you get up, you have a choice about how you want to live that day. I said, "I choose to be cheerful."

    "Let me give you an example," I continued. "Besides teaching here, I also teach at a college in Henderson, 17 miles down the freeway from where I live. One day a few weeks ago I exited the freeway and turned onto College Drive. I only had to drive another quarter mile down the road to the college. But just then my car died. I tried to start it again, but the engine wouldn't work. So I put my flashes on, took my books, and walked down the road to the college. When I got there, I called AAA(汽车协会) and asked for a tow truck to meet at my car after class. The secretary there asked me what had happened. "This is my lucky day," I replied, smiling.

    "Your car breaks down and toady is your lucky day? What do you mean?"

    "My car could have broken down anywhere along the freeway. I didn't," I replied. "Instead, it broken down at the perfect place: off the freeway, within walking distance of here. I'm still able to teach my class, and I've been able to ask for the tow truck to meet me after class! If my car was meant to break down today, it couldn't have been arranged in a more convenient way."

    I ended my story. In spite of the early hour, no one in my class seemed to be asleep. Somehow, my story had touched them.