I had been following the yellowish-green markers for a “popular and easy” three-mile out-and-back hike. Immediately after the trailhead(山道的起点), the trail became very rocky and steep. But having read information about the hike, I knew within five minutes, I was supposed to reach the hike's first overlook.

    However, the overlook never arrived. Instead, I found myself lost in the woods. Pulling out my cellphone, I saw it read “no service”. I checked the last text message I'd sent to my mom. It read, “Conference ended…going for a small hike before my flight home this afternoon.” I put my phone away and kept moving and yelling, “Help! Is anybody out there?” Every so often, I'd stop to listen, but I never heard a reply.

    I got out my phone again. The battery was running out fast as it searched for a signal. I struggled to find a place where I could get service. When I did, I called my mom. It went through! In a shaky voice, I said, “Mom?” And then the call dropped. More than 1,500 miles away, my mom instantly knew something was wrong. She called the Denver Police Department and was directed to the US Forest Service.

    This was how I was introduced to John, an operator from the US Forest Service. Following John's instruction on the phone, I finally escaped from the woods. I breathed a sigh of relief. Then my phone rang, and it was John, making sure I was still going in the right direction. “By the way,” he said, “we've had your mother on hold this whole time. We know once you get down the mountain, you will absolutely want to give her a call.”

    You may know the Eiffel Tower as one of the most famous man-made monuments in the world, and you'd be absolutely right! Read on to learn about the history of the great Eiffel Tower.

    Travelers from around the world flock(蜂拥)to Paris, France, to visit the Eiffel Tower, making it the most visited paid monument in the entire world! In fact, in 2010, the Eiffel Tower welcomed its 250 millionth visitor!

The history of the Eiffel Tower

    The Eiffel Tower was named after the engineer Gustave Eiffel, whose company designed and built the famous monument. Construction began in January of 1887 and was completed in only two years. Their plan was to finish the tower in time to be the entrance arch for the World's Fair in 1889. This fair celebrated the 100^th anniversary of the French Revolution, which took place from 1789 to 1799.

The height competition

    Located on the Champs de Mars, the tower is the tallest structure in Paris. It was the tallest man-made structure in the world for 41 years until the Chrysler Building in New York surpassed(超过) it. Then the spire(塔尖) on the top of the tower was added, raising its height to 17 feet taller than the Chrysler Building. It is now 1,063 feet tall! There are two replicas(复制品) of the Eiffel Tower in the world: a half scale model at the Paris Hotel in Las Vegas and a full-sized monument of a similar (but not exact) design in Tokyo, Japan.

Three shades of wonder

    Some pictures make the Eiffel Tower look like a dark iron color. But it is, in fact, bronze. Not only that, but the tower is actually painted three different shades to make it appear even taller: darkest on the bottom and lightest on the top.

    A machine that takes sweat-laden (浸满汗水的) clothes and turns the sweat into drinking water is in use in Sweden. The machine makes the clothes turn round quickly, heats them to remove the sweat, and then passes the steam through a kind of special material to make purified water.

    Since it has been brought into use, its creators say more than 1000 people have drunk others' “sweat” in Gothenburg. They add the liquid is cleaner than local tap water.

    The device was built for the United Nations' child-focused charity UNICEF to promote a campaign highlighting the fact that 780 million people in the world lack access to clean water.

    The machine was designed and built by the engineer Andreas Hammar, known locally for his appearances on TV tech show “Mekatronik”. He said the key part of the sweat machine was a new water purification part developed by a company named HVR.

    “It uses a technique called membrane distillation (膜蒸馏),” he told the BBC. “We use a special kind of material that only lets steam through but keeps bacteria, salts, clothing fibers and other things out. They have something similar to the International Space Station, but our machine is cheaper to build. The amount of water it produces depends on how sweaty the person is, but one person's T-shirt typically produces 10ml, about a mouthful.”

    The device has been put on show at the Gothia Cup-the world's largest international youth football tournament. Mattias Ronge, chief executive of Stockholm-based advertising agency Deportivo, said the machine had helped raise awareness for UNICEF, but in reality had its limitations.

    “People haven't produced as much sweat as we hoped – right now the weather in Gothenburg is lousy,” Mattias Ronge said. “So we've equipped the machine with exercise bikes and volunteers are cycling like crazy. Even so, the demand for sweat is greater than the supply. And the machine will never be produced in large numbers, since there are better solutions out there such as water purifying pills.”

    In today's world, English is the most wildly used language. It is our duty to learn English in the new situation of the reform and opening to the outside world. How can we master the English language? I'd like to give you some good advice.

    First, get interested in it. I enjoy listening to foreign friends talking when I was a child. At the same time I watched the English program Follow Me on TV. From then on, I kept on learning English. The more I learned, the more progress I made.

    Second, practice makes perfect. Many people study English very hard, but they are very shy to speak it in public, for they are afraid of making mistakes. Remember you have to make a mistake before you can correct it. A native English speaker makes mistakes sometimes, too.

    Third, the beginners should be encouraged to pay attention to idioms. The English language has many idioms. For example, you should say “ He is as strong as a cow.”

    If you are studying at school, do be a polite and clever student! There is no excuse for not doing your assignments. If you can't come to school, you should call your teacher or your classmate ask about homework. It is your responsibility to find out what homework you have missed. It is not the teacher's job to remind you of the missed assignments.

    You must not be absent on a test day. If you are seriously ill, call and let the teacher know you will not be there for the test. If your teacher allows a make-up test, you should take the test, again within one or two days after you return to class. Serious illness is the only reason for missing a test.

    Be on time! It is impolite to be late. Also, it bothers other students. If you must come in late, be sure to do it quietly. Have your books and papers out of your bag before you come into the classroom. Then go to your seat and sit down quietly. In the USA, it is not necessary to knock before you enter the classroom. Most teachers will give you a low grade if you are often late.

    In America, you should call your teacher by his or her last name instead of “teacher”. Also you should use Mr, Miss, Ms or Mrs before the last name (such as Mrs Smith or Mr Jones). The teacher will tell you the title that he or she likes. It is impolite in the USA to eat, drink or chew gum during class. Don't do these until the break. Also, removing your shoes in the classroom is not polite.

    Some people think the government should move the big companies and factories in cities to the countryside. To what extent do you agree?

    Due to the increased urbanization, there appears a bunch of heated social problems. Some people have noticed that there are many big companies and factories in the city and they believe that moving those big companies and factories into countryside could be a good way to solve many of the city problems, such as traffic issues and housing problems. However, I hold an opposite opinion to them and I will explain it as below.

    Cities have much more advantages than countryside. There are more cinemas, restaurants and shopping malls in cities, let alone better education and health care. Living in cities makes life more convenient and enjoyable. Thus not everyone is willing to move to countryside in spite of their companies' moving. They have got cars, which transfers them easily between work and home. Therefore, the pressure of traffic will not be released due to such solution. As for the available empty places spared by the big companies, the newest small companies will take good care of them—with the realization of the benefits that running a business in cities will bring to them. In other words, situation of housing will not be improved much.

    Besides, there will be more problems if big companies and factories move out. Where there are big companies and factories, there will be cities sooner or later. Consequently, countryside is to be disappearing. What's more, industrial pollution is not an easily mended problem.

    In conclusion, moving big companies and factories out of cities is never a final solution. It tackles(解决) no problem but causes lots of them. Just imagine. The traffic is still terrible, and there is no more scenic countryside. We should look into other ways to solve the problems.