In many big cities, there are usually more than one underground line(地铁线). The fastest way 1 in a city is by subway. How to travel by subway? Do you know? Here is some information 2 before you travel by subway. First, you should 3 the right line. If you don't, you will have to 4 and take another one. Second, you need some coins 5 your ticket, because 6 the machines which sell tickets only accept coins. Coins can be changed next to the ticket machines. Or you can go to the ticket office 7some. 8 you have a prepaid card, you can just go ahead. After you have bought the 9, you should wait for your subway outside the yellow line. You 10 walk too close to the yellow line. It's dangerous.
A city without cars would be very strange, right? But Venice is such a city.
Venice is in the northeast of Italy. It wasn't built on land like Beijing or Shanghai, but on more than 110 islands. Seawater is everywhere around the city.
Even so, travel isn't difficult. The water ways have always been the best way to get around. There are 177 canals and more than 400 bridges that can guide you to where you want to go. People in Venice move from place to place by boat. They like to enjoy the scenery and cool summer nights while taking boat trips. They can talk to other people as they go along.
Venice grew out of small islands in saltwater lakes when some Italians escaped from a war over 1,500 years ago, and built homes there.
Water makes the city special, but it is also a big problem. Sometimes tourists will have such strange experiences. One moment they walk across the Rialto Bridge, and there's nothing special. But when they come back to the bridge an hour later, it's underwater and everyone is wearing rain shoes.
Once, people used too much underground water. This made the city get lower little by little. Now the city has gone down by about 23 centimetres. Another problem is the rising seawater. The temperature has risen over the years. This has made the ice of the Arctic Ocean(北冰洋) melt(融化) .
Every year, high water hits the city in autumn and winter. When a lot of water comes, more than half of the city is underwater.
Scientists are trying different ways to stop the city from getting even lower. The Italian government has asked some of Italy's biggest companies to build the MOST project, which is planned to be built under the seawater to stop the rising water. Anyway, this project is helping solve the problem.
