【正文】 a chance to make a trip into space with my friend Li Yanping, an astronomer. We visited the moon in our spaceship!Before we leave, Li Yanping explained to me that the forece of the gravity would change three times on our journey and that the first change would be the most powerful. Then we were off. As the rocket rose into the air, we were pushed back into our seats because we were trying to escape the pull of the earth’s gravity. It was so hard that we could not say anything to each other. Gradually the weight lessened and I was able to talk to him. “ Why is the spaceship not falling back to the earth? On the earth if I fall from a tree I will fall to ground.” I asked. “ We are too far from the earth now to feel its pull, “ he explained, “ so we feel as if there is no gravity at all. When we get closer to the moon, we shall feel its gravity pulling us, but it will not be as strong a pull as the earth’s. “ I cheered up immediately and floated weightlessly around in our spaceship cabin watching the earth bee smaller and the moon larger.When we got there, I wanted to explore immediately. “ Come on,” I said. “ If you are right, my mass will be less than on the earth because the moon is smaller and I will be able to move more freely. I might even grow taller if I stay here long enough. I shall certainly weigh less!” I laughed and climbed down the steps from the spaceship. But when I tried to step forward, I found I was carried twice as far as on the earth and fell over. “ Oh dear,” I cried, “ walking does need a bit of practice now that gravity has changed.” After a while I got the hang of it and we began to enjoy ourselves.Leaving the moon’s gravity was not as painful as leaving the earth’s. But returning to the earth was very frightening. We watched, amazed as fire broke out on the outside of the spaceship as the earth’s gravity increased. Again we were pushed back hard into our seats as we came back to land. “ That was very exhausting but very exciting too,” I said. “Now I know much more about gravity! Do you think we could bisit some stars next time?” “Of course,” he smiled, “ which star would you like to go to?”Caught by a black holeThe spaceship warned Li Yanping and me to be ready as we were approaching the “black hole”. We could see some faint lights around what looked like an empty space. Li Yanping said, “ That empty hole is like a mouth always needing to be fed. Those lights are thins that are being pulled into time by the gravity of the hole.” We watched with interest and amazement at the lights which seemed to be going fainter and fainter round the edge of the black hole. Just then the lights on our spaceship went our the and the puter stopped working. What was happening? I tried to turn the spaceship away from the hole but it would not move. Would it eat us too?Suddenly the spaceship jumped and began to move round the edge of trhe hole too. The gravity of the “black hole” was pulling us into its “mouth”. As the spaceship moved round the black hole, I felt rather sick. My mouth went dry and I closed my eyes. All the stories about what happened when you were caught by the gravity of a “black hole” seem to be true.But then the spaceship jumped again. This time it moved sideways and away from this edge of the “black hole”. Someone watching me would have seen the spaceship flying like a bird away from the “black hole”. But we felt nothing. At last we were able to look around us. Luckily the puter had started working again. We realized that we had discovered something new about “black hole”. If you go inside the edge of a “black hole”, it will “eat” you and there is no escape。 but if you do not, you may have an opportunity to escape. How exciting!Unit 5A trip on “ The True North”Li Daiyu and her cousin Liu Qian were on a trip to Canada to bisit their cousins in Montreal on the Atlantic coast. Rather than take the aeroplane all the way, they decided to fly to Vancouver and then take the train west to east across Canada. The though that they could cross the whole continent was exciting.Their friend, Danny Lin, was waiting at the airport. He was going to take them and their baggage to catch “The True North”, the cross Canada train. On the way to the statiion, he chatted about their trip. “You’re going to see some great scenery. Going eastward, you’ll pass mountains and thousands of lakes and forests, as well as wide rivers and large cities. Some people have the idea that you can cross Canda in less than fice days, but they forget the fact that Canada is 5500 kilometers from coast to coast. Here in Vancouver, you’re in Canada’s warmest part. People say it is Canada’s most beautiful city, surrounded by mountains and the Pacific Ocean. Skiing in the Rocky Mountains and sailing in the harbour make Vancouver one of Canada’s most popular cities to live in. Its population is increasing rapidly. The coast north of Vancouver has some of the oldest and most beautiful forests in the world. It is so wet there that the trees are extremely tall, some measuring over 90 metres.”That afternoon aboard the train, the cousins settled down in their seats. Earlier that day, when they crossed the Rocky Mountains, they managed to catch sight of some mountain goats and even a grizzly bear and an eagle. Their next stop was Calgary, which is famous for the Calgary Stampede. Cowboys from all over the world e to pete in the Stampede. Many of them have a gift for riding wild horses and can win thousands of dollars in prizes.After two days’ travel, the girls began to realize that Canada is quite empty. At school, they had learned that most Canadians live within a few hundred kilometres of the USA border, and Canada’s population is only slightly over thirty million, but now they were amazed to see such an empty country. They went through a wheatgrowing province and saw farms that covered thousands of acres. Afrer dinner, they were back in an urban area, the busy port city of Thunder Bay at the top of the Gre