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.

    It is reported that conservation groups in North America have been arguing about the benefits and dangers of wolves. Some groups believe wolves should be killed. Other people believe wolves must be protected so that they will not disappear from the wilderness(荒野).

For Killing Wolves

    In Alaska，the wolf almost disappeared a few years ago，because hunters were killing hundreds of them for sport. However, 1aws were established to protect the wolves from sportsmen and people who catch the animals for their fur．So the wolf population has greatly increased. Now there are so many wolves that they are destroying their own food supply.

    A wolf naturally eats animals in the deer family. People in the wilderness also hunt deer for food. Many of the animals have been destroyed by the very cold winters recently and by changes in the wilderness plant life．When the deer can't find enough food，they die.

    If the wolves continue to kill large numbers of deer, their prey(猎物) will disappear some day. And the wolves will, too. So we must change the cycle of life in the wilderness to balance the ecology. If we killed more wolves, we would save them and their prey from dying out. We'd also save some farm animals.

    In another northern state, wolves attack cows and chickens for food. Farmers want the government to send biologists to study the problem. They believe it necessary to kill wolves in some areas and to protect them in places where there is a small wolf population．

Against Killing Wolves

    If you had lived long ago，you would have heard many different stories about the dangerous wolf．According to most stories，hungry wolves often kill people for food．Even today，the stories of the “big bad wolf” will not disappear．

    But the fact is wolves are afraid of people, and they seldom travel in areas where there is a human smell．When wolves eat other animals，they usually kill the very young, or the sick and injured. The strongest survive. No kind of animal would have survived through the centuries if the weak members had lived. And has always been a law of nature.

    Although some people say it is good sense to kill wolves，we say it is nonsense! Researchers have found wolves and their prey living in balance．The wolves keep the deer population from becoming too large, and that keeps a balance in the wilderness plant life.

    The real problem is that the areas where wolves can live are being used by people. Even if wilderness land is not used directly for human needs, the wolves can't always find enough food. So they travel to the nearest source, which is often a farm. Then there is danger. The “big bad wolf” has arrived! And everyone knows what happens next.

    What's small, buzzes here and there and visits flowers? If you said bees or hummingbirds, you got it. You wouldn't be the first if you mixed the two up. Now a group of researchers even say we should embrace our history of considering the two together in the same group. The way scientists study bees could help them study hummingbird behavior, too.

    Scientists first compared the two back in the 1970s when studying how animals search for food. The idea is that animals use a kind of math to make choices in order to minimize the work it takes to earn maximum rewards. Researchers at the time focused on movement rules, like the order in which they visited flowers, and where flowers were located relative to others .It was “almost like an algorithm（算法）”for efficient searching, said David Pritchard, a biologist at the University of St. Andrews in Scotland. Hummingbirds and bees had similar solutions.

    As the field of animal cognition（认知）appeared, hummingbird and bee research parted. Neuroscientists and behavioral ecologists developed ways to study bee behavior in naturalistic settings. Hummingbird researchers compared hummingbirds to other birds and borrowed methods from psychology to study their ability to learn in the lab. To be fair, hummingbirds and bees differ. For example, hummingbirds have more advanced eyes and brains than bees. Honeybees and bumblebees are social; hummingbirds typically aren't.

    But however they perceive（感知）or process information, they both experience similar information, Dr. Pritchard said. In day-to-day searching for food, for example, hummingbirds may rely on more of a bee's-eye view than a bird's-eye view. Like other birds, they rely on landmarks, distances and directions to make maps when travelling long distances, but they don't use these cues to find flowers. Move a flower just an inch or so away from where a hummingbird thought it was and it will hover over the flower's original location. Dr. Pritchard is investigating if, like bees, hummingbirds engage in view matching — hovering, scanning snapshots of a place to its memory and using those as references later.

    Now women are free to enter any career that attracts them, and working can bring them pride, confidence and independence. Working women make up nearly half of the U.S. workforce, and 51 percent of professional workers, like doctors, lawyers, nurses and accountants, are female. While climbing the career ladder can be rewarding, it often comes with one big disadvantage: weight gain!

    New research published this week in the International Journal of Obesity shows that working women are more likely to be overweight, and the more you work, the more pounds you're likely to pile on. Like many women, I work... a lot! As a self-employed nutrition communications specialist, I sit at my desk, in front of a computer, for hours on end. Sitting alone is one of the worst things you can do for your health, and it's directly linked to being overweight and increased fatness, so the fact that women in the workforce gain weight isn't that surprising. If you work, you have less time to move around. Obesity researchers are revealing many other ways that employment is harmful to your diet and waistline(腰围).

    In the International Journal of Obesity study, some 9,276 Australian women aged 45-50 had their body weight and employment status monitored for two years. Results? Those who worked more than 35 hours were likely to gain weight compared to those who worked fewer hours or were out of the workforce. What's more, the more hours a woman worked in a week, the more weight she gained.

    The authors of the Australian study attribute weight gain among working women to inactivity, lack of time for food preparation, more use of prepared foods, high levels of stress, lack of sleep and consuming more alcohol. I'll also add in travel, meals eaten out and working at night as other factors that I can find to make balancing work with a healthy diet a challenge.

    In 1973, I was teaching elementary school. Each day, 27 kids entered "The Thinking Laboratory." That was the name students voted for after deciding that "Room 104" was too dull.

    Freddy was an average student, but not an average person. He had the rare balance of fun and compassion(同情). He would laugh the loudest over fun and be the saddest over anyone's misfortune.

    Before the school year ended, I gave the kids a special gift, T-shirts with the words "Verbs Are Your friends" on them. I had advised the kids that while verbs may seem dull, most of the fun things they do throughout their lives will be verbs.

     Through the years, Pd run into former students who would provide updates on old classmates. I learned that Freddy did several jobs after his graduation from high school and remained the same caring person I met forty years before. Once, while working overnight at a store, he let a homeless man sleep in his truck. Another time, he lent a friend money to buy a house.

    Just last year, I was conducting a workshop when someone knocked at the classroom door. A woman excused the interruption and handed me an envelope. I stopped teaching and opened it up. Inside were the "Verbs" shirt and a note from Freddy's mother. "Freddy passed away on Thanksgiving. He wanted you to have this."

    I told the story to the class. As sad as it was, I couldn't help smiling. Although Freddy was taken from us, we all took something from Freddy.

    Jacob's Pillow Dance Festival

    Where: Becket, Massachusetts

When: Jun.15—Aug.24

    Each summer, this influential dance center presents a number of classes and performances by more than 50 companies from around the world. Highlights (最精彩的部分) in this season include the Dance Theater of Harlem's production of Alvin Ailey's "The Lark Ascending", which opens the festival.

    Many events are free. Ticketed performances start at $22. Jacobspillow.org.

    Moab Music Festival

    Where: Moab, Utah

When: Aug.29—Sept.9

    This area is better known for mountain biking than for music. But since 1992, it has hosted a private festival that brings classical, jazz, Latin and other types of music to the land. This year there will be 16 concerts, including three "Grotto Concerts", where guests take a 45-minute boat ride down the Colorado River to performances.

    Events start at $25. moabmusicfest.org.

    Cheyenne Frontier Days

    Where: Cheyenne, Wyoming

When: July19—28

    There is something for everyone at this 117-year-old festival, from an "Indian village and Old West museum" to country concerts. But the competition is still the main attraction, with cowboys and cowgirls competing for major money in the world's largest outdoor stage.

    Competition tickets start at $18, and concert tickets at $23. cfdrodeo.com.

    The Glimmerglass Festival

    Where: Cooperstown, New York

When: July6—Aug.24

    Each summer, opera lovers from around the country (and the world) travel to upstate New York to watch productions that include stars like Nathan Gunn and Ginger Costa-Jackson. This year's performances include Wagner's "The Flying Dutchman" and Verdi's "King for a Day", in honor of the 200th birthdays of both composers(作曲家).

    Tickets start at $26. glimmerglass.org.