Denali National Park, Alaska

    History

    Within Denali National Park, the Toklat River will always have a special significance, as it was the location where naturalist Charles Sheldon built a cabin and was so moved that he fought to preserve the land. He moved back east and spent nine years lobbying (游说）to create Alaska's first national park.

    When to Visit

    To avoid the crowds, visit in June, but keep in mind that there are up to 21 hours of sunlight in Alaska in summer. If it seems like a bit much for your taste, try visiting in late August or September.

    If you visit to climb Mount McKinley, May and early June are the best times to climb.

    Major Attractions

    It is difficult not to see Denali's largest attraction towering 20,320 feet high. Mount McKinley can even be seen up to 70 miles away on a clear day. If you brave the climb to the top, you will be rewarded with charming views of the Alaska Range.

    Sable Pass is a prime spot to view grizzly bears. Closed to off-road foot traffic, the area is popular for bears feeding on berries, roots, and even occasionally on other mammals.

    Beginning at just below the summit of Mount McKinley, Muldrow Glacier flows 35 miles through a gorge and across the tundra. Twice in the last hundred years, the Muldrow has surged (涌动）, most recently in the winter of 1956-1957.

Accommodation

    Five campgrounds are located within the park, and many are open from late spring to early fall.Note: reservations are strongly recommended during summer. Riley Creek campground is open all year round, and all but two (Sanctuary and Wonder Lake) offer RV (可供居住的大篷车）sites.

    Also within the park are a few lodges (旅馆）—North Face Lodge, Denali Backcountry Lodge and Kentishna Roadhouse.

    Living in a new country means experiencing a different way of life{#blank#}1{#/blank#} The cultures of all countries are unique, which means that people who have grown up in different places will have different ways of behaving, different ways of thinking about things and different ways of expressing themselves. Before you travel, it is useful to think about culture and the things that are affected by it {#blank#}2{#/blank#}

    Culture is the values, attitudes, behaviors and beliefs shared by a group of people{#blank#}3{#/blank#} We learn about the culture of our own society in a very natural way as we grow up-we learn through “do's” and “don'ts” about how we treat people, how we behave and what we believe in as children.

    {#blank#}4{#/blank#}You can see some parts of an iceberg-just like you can see some parts of a country's culture when you visit it. For example, you can see different ways of greeting people, hear different languages and observe different festivals and customs. However, a much bigger part of every iceberg is hidden under water. Even though this part of the iceberg is hard to see, it is very important -without it, the iceberg would not exist. The same is true of culture. There are many aspects of it which you cannot see when you visit a different country, for example the nature of friendship and the importance of time.

    {#blank#}5{#/blank#} It will take a long time to understand those values and beliefs because you have to work them out, but it is probably the most interesting part of any time you spend abroad.

A. Culture is like an iceberg.

B. Different people have different cultures.

C. Doing so will help you prepare for living in a new country.

D. Some people like to travel to new countries and settle down.

E. The aspects of culture you can see are based on those values and beliefs that you cannot see.

F. This means that culture is like a kind of glue (胶水)that holds society together.

G. This is very exciting and interesting, but it can also be a little challenging at times.

    Wetlands are ecosystems found in low, flat areas. Often they border ponds, rivers, lakes, and oceans. Wetlands include marshes, swamps, and bogs.

    No trees grow in a marsh, but there are lots of grassy plants. Ducks, turtles, and many different bugs (虫子) live there, too. Florida has the world's biggest freshwater marsh. The Everglades covers 4,000 square miles. The Everglades is not entirely fresh water, however. Near the sea the fresh water and salt water mix. Some plants and animals can live only in this brackish water.

    Saltwater marshes lie along the East Coast and the Gulf of Mexico. During high tide these marshes are under water. During low tide these marshes can be seen. The water rushes out, carrying bits of plants, dead animals, and minerals necessary for sea animals. Many plants and animals depend upon this ever-changing environment.

    Swamps are forested wetlands. Like marshes, they are often found near rivers or lakes and have mineral soil that drain very slowly. Unlike marshes, they have trees and bushes. Swamps have trees that grow with their roots underwater. But the trees will die if their roots stay underwater too long. Animals such as water snakes and frogs live in swamps.

    Bogs have damp, soft soil. So many dead plants have piled up that there is no longer any standing water. This rotting plant matter turns into peat (泥炭). In Ireland and Scotland peat is dried and burned to heat homes. Bog soil is useful for growing wild rice. Lots of insects live there.

    Most people do not find wetlands beautiful. But wetlands are important. Marshes and swamps store water, thus reducing the flooding a heavy rain can cause. About one-third of all of America's endangered plants and animals live in wetlands. Now laws protect some wetlands. More than a dozen wetlands in the US are refuges (保护区) and wildlife preserves.

    Many science fiction stories tell about explorers arriving in a new world. The explorers then use some kind of high-tech device to test for breathable air or signs of life. But here on Earth, science fiction is becoming reality through a new sampling technology called environmental DNA, or eDNA for short. Scientists can use it to identify rare species or estimate fish populations with just a little air or water.

    Environmental DNA can be used in two ways. One is to identify the creatures that live in a certain place. The other is to confirm the presence or lack of a specific creature.

    Caren Goldberg is one of the first biologists to take the technology from the testing stage to actually using it. She sees eDNA as a way to get answers more efficiently and with less destruction compared to traditional survey techniques. Until recently, scientists depended on snorkeling ( 潜水), netting or using an electric current to temporarily catch fish.

    This newer way to identify what lives in the environment is becoming popular around the world. Animal experts in Vietnam are using the eDNA to find the last, wild Yangtze giant softshell turtles. One researcher on the Caribbean island of Trinidad is using the sampling technology to find endangered golden treefrogs. In Madagascar, it is being used to identify amphibian(两栖动物)diseases.

    Ms Goldberg has used eDNA testing to confirm the local extinction (灭绝) of a leopard frog in the American state of Idaho. She has also been asked to document the spread of the New Zealand mudsnail in the state of Washington. The creature has been found in lakes and other waterways across the state.

    Scientists working with the technology say they do not expect robots to replace field biologists anytime soon. But the old-fashioned field work could soon be more targeted.

Tips to fight summer weight gain

    When we think of summer, most of us think of outdoor fun. So it seems like we should naturally lose weight over the summer—not gain it. {#blank#}1{#/blank#} Lots of summer activities can work against our efforts to stay at a healthy weight. The good news is that it's easy to avoid problems if we know what to look out for.

    Get going with goals. When we don't have a plan, it's easy to spend summer moving from couch to computer, with regular stops at the fridge. {#blank#}2{#/blank#} Just be sure to plan for some downtime so you can relax a little!

    {#blank#}3{#/blank#} With school out, we lose our daily routines. If you don't have a specific job or activity to get up for, it's easy to sleep late, watch too much TV, and snack more than usual. Make sure your summer days have some structure — like getting up at the same time each day and eating meals at set times. Plan activities for specific times, like exercising before breakfast, for example. If you have time on your hands, offer to make dinner a couple of nights a week so your family can enjoy a sit-down meal together.

    Think about what and how you eat. Summer means picnics and barbecues — activities that revolve around an unlimited spread of food. Pace yourself. Don't overload your plate. Avoid going back for seconds and thirds. Choose seasonal  healthy foods like fresh fruit instead of high-sugar, high-fat desserts. {#blank#}4{#/blank#}

    Stay busy. {#blank#}5{#/blank#} In addition to helping you avoid the cookie jar, filling your days with stuff to do can give you a sense of accomplishment. That's especially true if a dream summer job or planned activity fell through. Limit your screen time — including TV, computer, and video games — to no more than 2 hours a day.

A. Stick to a schedule.

B. Plan more activities.

C. Appropriate summer eating sets you up on the right track!

D. Most of us, however, don't take summer weight gain seriously.

E. In reality, though, summer isn't all about beach volleyball and water sports.

F. When we're bored, it's easy to fall into a trap of doing nothing and then feeling low on energy.

G. Avoid this by setting a specific aim, like volunteering, mastering a new skill, or working at a job.

    Feeding birds is a popular way to watch wildlife. But experts say it might put wild birds at risk.

    Feeding birds is not necessary for their survival except in extreme weather conditions. Feeders(喂食器)can definitely help birds get through that kind of weather. But most birds eat insects and show little interest in bird feeders. For those birds, we can grow native plants in a natural environment. Birds which are fond of eating seeds will be more likely to come to feeders if there is some cover nearby. This lets them feed and then fly to protective areas, such as in trees.

    The most common mistake people make with their bird feeders is that they put feeders in places where birds are easily frightened by passers-by, risk being hurt by cats, or risk flying into windows.

    So set up a bird feeder at least one meter away from a window. That way, if a bird gets frightened, it won't get killed when it hits the glass. Owners of cats should keep them inside home so they can't hurt the birds.

    Some birds are more aggressive at feeders. They eat a lot and do not leave much food for other birds. A solution is to put the food in more than one place by using different kinds of seeds or fruits. This can also increase the number and diversity of birds in your neighborhood. But don't feed wild birds anything salty, like potato chips, or food that could choke them, like bread.

    Pay attention to food quality and freshness. Unprotected food left too long in feeders will turn moldy(发霉), which can kill wildlife.

    Another word of advice: Always provide a supply of clean water for birds, but use care when looking for the right birdbath. If the birdbaths are too deep for birds, putting a few large stones in the water can give the birds a place to sit.