Radar is an electronic device that detects planes, ships, coastlines, landmarks, and even storm clouds. The name radar comes from the first letters of the words radio direction and ranging. As the human eye uses light waves to see, radar “sees” with radio waves. Without radar, planes could not land safely in bad weather and ships could not move safely in thick fog{#blank#}1{#/blank#}

    In the 1800s it was discovered that radio waves could be reflected from objects. But scientists did not make great advances in radar research until the 1930s, when the world was threatened by war{#blank#}2{#/blank#} It has been used widely in almost every conflict since then.

    Echoes make it possible for radar to work. When a beam of radio waves is sent out, it strikes on an object and returns an echo. This echo is picked up by radar and recorded on a screen similar to television screen. On the screen an observer sees a flash, or a blip, that shows the direction and distance of the object.{#blank#}3{#/blank#}

    Airport control towers use radar to guide planes in for safe landings. Almost all large ships depend on radar to prevent collisions with icebergs or other ships{#blank#}4{#/blank#}Weather forecasters “see” the size, direction, and speed of storms on radar screens. Astronomers can even use radar to measure accurately the distance to the moon. Thus, the device has generated major advancements.

    {#blank#}5{#/blank#}Huge radar antennas have been installed all over the United States. They guard us against possible enemy attacks. We have ballistic—missiles (战略导弹)warning systems that can alert us to attacks when missiles are more than 1,000 miles away. Other radar systems warn us against enemy aircraft and even spying space satellites.

A. Police track speeders in radar-equipped cars.

B. These measurements are now highly accurate.

C. The device can be used in a wide range of fields.

D. It is therefore especially valuable to shippers and travelers.

E. During World War II many countries used radar effectively.

F. Today radar is used by commercial airliners and weather forecasters.

G. Strengthening national defense is one of radar's most important functions.

                                                                                      The Lifecycle of a T-shirt

    We all probably have a lot of T-shirts, but do you ever stop and think about the influence of a T-shirt on the planet? You'd probably be surprised to learn what's involved in the lifecycle of just one T-shirt.

    There are 5 major stages: material, production, shipping, use and disposal. The material stage involves farming, irrigating, fertilizing, harvesting and ginning. While cotton is a natural fiber (纤维) and not as harmful to the environment as manmade fibers, it still takes a toll in the material and production stages. Commercial cotton farming uses a large amount of water, and the use of pesticides (杀虫剂) is widespread across the globe, especially in cotton farming. Studies have shown that farmers spend around $4.1 billion on pesticides annually, of which 25% was spent on cotton crops in the US.

    Once the cotton is grown and harvested, so begins the production stage: spinning, knitting, bleaching, dyeing, cutting, sewing, etc.——these processes also use a great deal of water and energy. Commercial dyes and bleaches are harmful pollutants and can eventually pollute groundwater.

    After the T-shirt is produced, it enters the transportation stage. This often involves overseas shipping. Take a look in your closet. Chances are that most of your cotton garments (衣服) are made in China or India. Garments can be shipped via plane, ship or truck…, all of which spill CO₂ into the atmosphere. Calculations show that CO₂ emissions from light trucks alone amount to 1.15 pounds per mile.

    Once the T-shirt reaches the retail market, it is purchased. This stage may seem like the leastenvironmentally damaging part. But consider the number of times you've washed and dried your favorite T-shirt. Washing machines are certainly becoming more efficient. However, the average American household does 400 loads of laundry per year, using about 40 gallons of water per load. Such excessive water use is combined with the large amount of energy used by dryers.

    The final stage of life is disposal. This releases harmful emissions, or involves a landfill where cotton takes years to break down. Current US records show that an estimated 15% of clothes and shoes are recycled, which means that consumers send a shocking 85% of these materials to landfills.

    We all need new clothes every once in a while, but let's all try to keep in mind what goes into the production of clothing... It has a real impact on the planet.

    There are a lot of things you can do to help reduce your impact. Reuse and recycle clothes. If they're too worn out to wear, cut them up and use them as cleaning rags. Donate them to charity or another organization that recycles textiles. When possible, make an effort to buy organic cotton. Turn down the thermostat on your washer, and line dry your clothes when the weather will allow it.

—Hard to say. Doctors are trying their best.

    Grey clouds move as low as smoke over the treetops at Lolo Pass. The ground is white. The day is June 10.It has been snowing for the past four days in the Bitterroot Mountains.Wayne Fairchild is getting worried about our trek over the Lolo Trail-95 miles from Lolo Montana to Weippe in Idaho, across the roughest country in the West. Lewis and Clark were nearly defeated 200 years ago by snowstorms on the Lolo. Today Fairchild is nervously checking the weather reports. He has agreed to take me across the toughest, middle section of the trail.

    When Lewis climbed on top of Lemhi Pass,140 miles south of Missoula, on Aug.12,1805,he was astonished by what was in front of him; "high mountain chains still to the West of us with their tops partially covered with snow.＂Nobody in what was then the US knew the Rocky Mountains existed, with peaks twice as high as anything in the Appalachians back East.

    Today their pathway through those mountains holds more attraction than any other ground over which they traveled, for its raw wilderness is an evidence to the character of two cultures:the explorers who braved its hardships and the Native Americans who prize and conserve the path as a sacred (神圣的)gift. It remains today the same condition as when Lewis and Clark walked it.

    The Lolo is passable only from July to mid-September. Our luck is holding with the weather, although the snow keeps getting deeper. As we climb to Indian Post Office, the highest point on the trail at 7,033 ft, we have covered 13 miles in soft snow, and we hardly have enough energy to make dinner. After a meal of chicken, I sit on a rock on top of the ridge .There is no light visible in any direction, not even another campfire. For four days we do not see another human being. We are occupied with the things that mix fear with joy. In our imagination we have finally caught up with Lewis and Clark.

    Grey clouds move as low as smoke over the treetops at Lolo Pass. The ground is white. The day is June 10.It has been snowing for the past four days in the Bitterroot Mountains.Wayne Fairchild is getting worried about our trek over the Lolo Trail-95 miles from Lolo Montana to Weippe in Idaho, across the roughest country in the West. Lewis and Clark were nearly defeated 200 years ago by snowstorms on the Lolo. Today Fairchild is nervously checking the weather reports. He has agreed to take me across the toughest, middle section of the trail.

    When Lewis climbed on top of Lemhi Pass,140 miles south of Missoula, on Aug.12,1805,he was astonished by what was in front of him; "high mountain chains still to the West of us with their tops partially covered with snow.＂Nobody in what was then the US knew the Rocky Mountains existed, with peaks twice as high as anything in the Appalachians back East.

    Today their pathway through those mountains holds more attraction than any other ground over which they traveled, for its raw wilderness is an evidence to the character of two cultures:the explorers who braved its hardships and the Native Americans who prize and conserve the path as a sacred (神圣的)gift. It remains today the same condition as when Lewis and Clark walked it.

    The Lolo is passable only from July to mid-September. Our luck is holding with the weather, although the snow keeps getting deeper. As we climb to Indian Post Office, the highest point on the trail at 7,033 ft, we have covered 13 miles in soft snow, and we hardly have enough energy to make dinner. After a meal of chicken, I sit on a rock on top of the ridge .There is no light visible in any direction, not even another campfire. For four days we do not see another human being. We are occupied with the things that mix fear with joy. In our imagination we have finally caught up with Lewis and Clark.

    What can keep your brain young and active? Marie Pasinski{#blank#}1{#/blank#} doctor from Massachusetts General Hospital, says, “New experiences as well as a good snack.”

    The next time you feel{#blank#}2{#/blank#} (bore) at the pool, play a board game or cards. Exercising your mind with a challenging game that requires brainpower,{#blank#}3{#/blank#} chess or bridge (桥牌), is more than just fun. These types of games are so interesting{#blank#}4{#/blank#} they can build up working memory. Traveling, especially in the places where English isn't spoken, can make you{#blank#}5{#/blank#} (smart) and more intelligent. There is a great deal of recent research proving its benefits.

    {#blank#}6{#/blank#} the other hand, eat more nuts! Not only are nuts the perfect snack for a summer road trip, they also keep your mind sharp. Some nuts are rich in magnesium(镁),{#blank#}7{#/blank#}can improve learning skills and memory of mice. The research{#blank#}8{#/blank#} (publish) in the Journal Neuron last month. Another study at New York State Institute also proved the point{#blank#}9{#/blank#} (show) that mice who ate nuts made improvements in learning, memory, emotional regulation and movements, compared with{#blank#}10{#/blank#} who didn't eat nuts.

    What can keep your brain young and active? Marie Pasinski{#blank#}1{#/blank#} doctor from Massachusetts General Hospital, says, “New experiences as well as a good snack.”

    The next time you feel{#blank#}2{#/blank#} (bore) at the pool, play a board game or cards. Exercising your mind with a challenging game that requires brainpower,{#blank#}3{#/blank#} chess or bridge (桥牌), is more than just fun. These types of games are so interesting{#blank#}4{#/blank#} they can build up working memory. Traveling, especially in the places where English isn't spoken, can make you{#blank#}5{#/blank#} (smart) and more intelligent. There is a great deal of recent research proving its benefits.

    {#blank#}6{#/blank#} the other hand, eat more nuts! Not only are nuts the perfect snack for a summer road trip, they also keep your mind sharp. Some nuts are rich in magnesium(镁),{#blank#}7{#/blank#}can improve learning skills and memory of mice. The research{#blank#}8{#/blank#} (publish) in the Journal Neuron last month. Another study at New York State Institute also proved the point{#blank#}9{#/blank#} (show) that mice who ate nuts made improvements in learning, memory, emotional regulation and movements, compared with{#blank#}10{#/blank#} who didn't eat nuts.

    27- year - old Ross OC Jennings has become an online celebrity for his bagpipe-playing (演奏风笛) photos across the globe. He calls1 the First Piper.

    The seed for the world traveling idea 2 him when he attended a travel expo in London, where he met adventurers who shared their 3 from across the globe. Ross was attracted by their stories.

    The 4 began on a night in Tunisia in May 2014 by chance. Ross 5 his bags without knowing much about the North African country.6Tunisia, he traveled across Western Europe, the mountains of China, played in front of the Taj Mahal in India and Cambodians ancient temples. But his greatest7was in Kenya.

    On the way to Nairobi, Ross arrived at a famous 8 sanctuary (禁猎区) and hotel in Kenya. He begged the hotel owners to ask if he could play the bagpipes there. They answered 9“Of course the house was built by a Scotsman.” “the minute I started playing all these giraffes started 10towards me, rocking. It was the most 11 audience I've ever had.

    Ross has three 12when traveling. First, pipe in a school to interact with students; second, challenge himself to play in a dramatic place; and last, play in public. His Facebook is filled with 13 taken from around the world.

    Ross's journey is all 14 thanks to his unique music career, which started at the 15 of thirteen when he was offered the chance to play bagpipes at school. After leaving university, he16“the last thing I wanted to do was work behind a desk”. Inspired by the travel expo and equipped with his bagpipes, he made his wish to 17a real desk.

    18 planning what to do in the countries Ross visits, the plans seem to find him. He said, “Chance is a big part of it. That's why I partly, intentionally, don't try to plan too much.” The music connects people in uncommon and wonderful 19“Without having this dripping in clichés（陈词滥调）, it is amazing how 20 does connect people and how it makes people smile,” Ross said.

    The Republic of Vanuatu is an island nation located in the South Pacific Ocean. It was one of the poorest nations in the region. Within the last five years, however, it has become a hot spot for adventure travelers. In 2006 it was voted the happiest place on Earth. The reason is not that Vanuatu are the richest but that Vanuatu has white-sand islands, clear waters, the world's most accessible live volcano, great diving and food that grows faster than it can be picked.

    With a population of about 221,000, Vanuatu has 113 languages, which is a result of 3,000 years of immigration from many Pacific countries. There are three official languages: English, French, and Bislama. Bislama developed from South Pacific English, a simplified language that traders and other foreigners used it to communicate with speakers of the many local languages.

    Most of the islands are mountainous and of volcanic origin. There are several active volcanoes in Vanuatu, including Yasur on the island of Tanna, one of the world's most accessible volcanoes. If you've ever fancied getting close to a volcano, here's your chance.

    Vanuatu Post's Underwater Post Office has quickly become one of the busiest post offices for postcards in the world! Visitors from around the world want to experience the world's first under- water post office. The Post Office is only 50 meters offshore and at just three meters below the surface, very appealing to the young and young at heart. Since opening in 2003, the underwater post office has received about 100,000 visitors. They have posted one of the waterproof（防水的）postcards available in Vanuatu; these cards are collected regularly by one of Vanuatu Post's four trained divers. The underwater branch is manned daily for usually about an hour, longer with demand.

    The Republic of Vanuatu is an island nation located in the South Pacific Ocean. It was one of the poorest nations in the region. Within the last five years, however, it has become a hot spot for adventure travelers. In 2006 it was voted the happiest place on Earth. The reason is not that Vanuatu are the richest but that Vanuatu has white-sand islands, clear waters, the world's most accessible live volcano, great diving and food that grows faster than it can be picked.

    With a population of about 221,000, Vanuatu has 113 languages, which is a result of 3,000 years of immigration from many Pacific countries. There are three official languages: English, French, and Bislama. Bislama developed from South Pacific English, a simplified language that traders and other foreigners used it to communicate with speakers of the many local languages.

    Most of the islands are mountainous and of volcanic origin. There are several active volcanoes in Vanuatu, including Yasur on the island of Tanna, one of the world's most accessible volcanoes. If you've ever fancied getting close to a volcano, here's your chance.

    Vanuatu Post's Underwater Post Office has quickly become one of the busiest post offices for postcards in the world! Visitors from around the world want to experience the world's first under- water post office. The Post Office is only 50 meters offshore and at just three meters below the surface, very appealing to the young and young at heart. Since opening in 2003, the underwater post office has received about 100,000 visitors. They have posted one of the waterproof（防水的）postcards available in Vanuatu; these cards are collected regularly by one of Vanuatu Post's four trained divers. The underwater branch is manned daily for usually about an hour, longer with demand.