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    Visiting London can be an expensive trip, so establishing a budget and finding bargains when you arrive will help you get around London on the cheap. The following steps can help you find cheaper alternatives for transport for your London trip.

    Familiarize yourself with the city's boroughs(区) and determine specifically the area where you will be staying. You can use a street map, or an online map search engine, to establish where in the city you will be staying and the distance you are from the major tourist attractions you want to visit.

    Find a local provider of Transport for London tickets or travel cards, since your first bargain purchase will be an Oyster card. Travelling around London with an Oyster card will give you access to the cheapest option of transportation methods and the Oyster card is accepted citywide on buses, boats and the London underground, known by the locals as "the tube".

    Seek out your nearest tube station. The tube is the cheapest and most reliable form of transportation and runs from around 6 am until around 1 am, depending on the line or the station.

    There are 287 tube stations in London that accept the Oyster card, with a high concentration in Central London. If you are staying anywhere in Central London, there will be a tube station less than 10 minutes away.

    The Transport for London website offers a tube station search facility to find the nearest subway station to any location in the city. When you find a tube station, you can easily locate the closest bus stop by using the comparison bus-tube maps at the station's entrance.

    Follow the Transport for London Tube Guide to your destinations and always plan ahead. Making a plan for transport will save you unnecessary expenses, wasted trips on the tube and doubling back on your journey.

    Ireland has had a very difficult history. The problems started in the 16th century when English rulers tried to conquer (征服) Ireland. For hundreds of years, the Irish people fought against the English. Finally, in 1921, the British government was forced to give independence to the south of Ireland. The result is that today there are two "Irelands". Northern Ireland, in the north, is part of the United Kingdom. The Republic of Ireland, in the south is an independent country.

    In the 1840s, the main crop was affected by disease and about 750,000 people died of hunger. This, and a shortage (短缺) of work, forced many people to leave Ireland and live in the USA, the UK, Australia and Canada. As a result of these problems, the population fell from 8.2 million in 1841 to 6.6 million in 1851.

    For many years, the majority of Irish people earned their living as farmers. Today, many people will work on the land but more and more people are moving to the cities to work in factories and offices. Life in the cities is very different from life in the countryside, where things move at a quieter and slower pace.

    The Irish are famous for being warm-hearted and friendly. Oscar Wilde, a famous Irish writer, once said that the Irish were "the greatest talkers since the Greeks". Since independence, Ireland has revived (复兴) its own culture of music, language, literature and singing. Different areas have different styles of old Irish songs which are sung without instruments. Other kinds of Irish music use many different instruments such as the violin, whistles, etc.

    Easter Island's large and mysterious stone statues (雕像) have made it world famous. These statues, whose likenesses look like humans with huge stone cylinders (圆筒状物) balancing on their heads like hats, have tourists coming from all over the world. The tourists come to see these works of ancient art carved by the early inhabitants of the island. They come to see the mystery that has puzzled historians for decades.

    Easter Island is located in a remote part of the South Pacific Ocean about 2,300 miles west of Chile. Easter Island covers just 45 square miles and its Polynesian name is Rapa Nui.

    On Easter Sunday 1722, a Dutch explorer named Jacob Roggeveen was the first European to see Easter Island. The early Polynesians carved the statues within the holes of the volcano using only stone tools. Then they moved these huge statues to various destinations throughout the island. These 600 statues range in height from 10 to 40 feet. Some of them weigh as much as 50 tons. How could the early Polynesians lift hundreds of heavy statues out of the volcano? How did they move them across the island to their various locations? All of these questions, as well as many others, remain unanswered.

    The early islanders probably worshiped (崇拜) these eyeless giants until sometime around 1670. In 1680, a war broke out between two groups of islanders. The victors of the war and ancestors of the present inhabitants, broke down many of the statues. In most cases, they broke the necks of the statues.

    Now 15 of the statues on Easter Island have been repaired to their original positions on their stone platforms. Even today, using modern tools and machinery, putting up such large statues and balancing cylinders on top of their heads presents a challenging task.

    For thousands of years, people have tried to control water by building dams. Dams allow people to collect and store water for use at home, in industry, and in agriculture. For example, when people build a dam on a river, a reservoir(水库) collects water that can be channelled for human needs. In addition, the ability of dams to control water flow helps prevent floods. Dams can also be used to make electricity.

    As the human population grows, the need for water and electricity increases. So many new dams have been built in the past 50 years. Today, nearly half of the rivers in the world have at least one large dam. If managed well, dams can be a great benefit to people. Some dams, however, may do more harm than good.

    All dams cause changes in river ecosystem that has an impact on surrounding land and people. As river water collects behind a large dam, it may back up and form a large lake, flooding land and killing plants and animals. People living on land upstream of a dam may be forced to abandon their homes. Below the dam, water flow decreases. This changes the downstream ecosystem. Plants and animals may not have enough water. Some types of fish may be unable to move upstream to reproduce. Rare species of plants and animals may become endangered. Farmers living downstream from the dam may not be able to grow crops. People who fish for a living may have to find other work.

    An independent organization called World Commission on Dams worked during the late 1990s to suggest ways of reducing problems caused by some large dams. The commission recommended that the research, the group decision-making, and the creation of a plan all take place before the start of construction of a large dam. For a plan to be successful, it would need to demonstrate that the dam would contribute to the long-term improvement of human life. The likely impact of the dam on local people and the environment would be assessed and considered in the decision-making process.