听力原文： For more than two hundred years people have been using trains. There are trains to carry people, trains to carry animals. There are fast trains, slow trains, trains that go under the ground, trains that go through mountains. In busy cities, trains have been put under the ground. The subway trains run on tracks through huge tunnels under the noise and traffic of the city. The monorail is another kind of train used in busy places. The train hangs from a rail high above the streets and it carries people quickly in and out of the city. Railroad tunnels which are miles long have been built through mountains. Do you think these tunnels are ready to build? They are not. Workers spend many years on the job. Is it possible for a train to travel over water? Yes, it is. Great bridges have been built just for trains. And railroad tunnels have been built under the water. Some trains travel great distances. You can travel for 2,461 miles on Australia's trains which go across the continent or you can ride 6,000 miles across Russia. Today's trains have nice little bedrooms and dining rooms for people who travel long distances. Years ago trains were used to carry important people. These trains had beautiful bedrooms, bathrooms, dining roans, and sitting rooms. They were like Hale palaces really fit for a king. You have probably seen freight trains. There are many kinds. There are trains to carry logs, refrigerator trains to carry food, tank trains to carry fuel, even trains to carry cars. Some trains carry trucks and take them to other places. Then the trucks can travel on the roads. Trains have long been useful to men and women and to children. Many children have model trains. With the model trains they can build their own railroads and enjoy the wonderful world of trains. (23)