Steel, concrete(混凝土) and glass are the usual materials in any skyscraper. But more high buildings are now using wood.

    In the last four years, Australia, Norway, England and Canada have all built wooden skyscrapers. The latest one is in Sweden, a new, 19-storey wooden hotel called "Sida vid Sida" (Side by Side).

    Why are wooden skyscrapers being chosen ahead of concrete ones? Let's find out.

    Is it strong enough?

    Wood has been used in many Chinese buildings for thousands of years, but is it strong enough for skyscrapers?

    "There's a lot of new materials made out of wood that are able to build big buildings," material expert Dr Michael Ramage told CNN when he was interviewed.

Architects (建筑师)have done thousands of experiment to make sure it is. They place layers of wood across one another coated with special glue to create very strong material.

Wood also lasts a long time and doesn't break down if it is well looked after. The examples include the rooftops of Beijing's Forbidden City and some 700-year-old houses in England.

Ramage also said on the internet that bamboo could be cut in special ways to make it even stronger than normal wood.

    Won't it catch fire?

    Wooden buildings sound dangerous when it comes to fire. But experts say they may be safer than concrete ones if there is a fire.

    "Wood doesn't burn in the way the public imagines," Ramage said. Very small pieces of wood catch fire easily, but very big pieces of wood are quite hard to set on fire, he said.

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    Many people think the camel stores water in its hump (驼峰), but it does not. Instead, the camel stores something else there—food. The camel's hump is really a hump of fat (脂肪). The camel is often called "a ship of the desert". When the camel is not travelling and is in a place where there is much food and water, it eats and drinks a lot. As it does so, its hump rises from the fat its body makes. Then, when the camel is travelling through the desert and when there is no food, it can live off the stored fat.

    A camel can go on for days or weeks with little food or water. However, when its hunger reaches the starvation (饿死)point, its hump shrinks (收缩) and may even slip off its back and hang down its side.

    Camels are not fussy (挑剔的) about what they eat. Thorny (多刺的) plants don't hurt their mouths, grass of any kind will do and so will hay, dry grain and cactuses (干草, 干粮, 仙人掌).

There are one­ hump camels and two­ hump camels. Camels with one hump are called Arabian camels. They come from North Africa. Camels with two humps are from Asia.

    Endangered dolphins are beautiful animals that needed to be saved. It may interest you to know there are about six different types of dolphins that are endangered. Many of them are river dolphins and they are very close to being lost forever if we do not take the time to care for them. The following is the reason why they are in danger.

    {#blank#}1{#/blank#}Dolphins can often get stuck(卡) in these nets and they may die. Another problem is the fact that many people and different countries will hunt for dolphins as food.

    {#blank#}2{#/blank#}When the oceans and rivers are polluted, it affects the very environment where these beautiful creatures are living. It may be important to also keep in mind that the dolphin is towards the top of the food chain.{#blank#}3{#/blank#} If these small animals are affected by the pollution as well, there really is no safe place for the dolphin to go.

    {#blank#}4{#/blank#}You can also pay attention to the land around you. Do not litter and stop if you do. Spend time on the weekend cleaning up trash in your area and recycle what you can. You play a large role in this whether you believe it or not. So, find out what your role is related to endangered dolphins and work towards a positive change.

    The best time to collect green leaves is early in the leafing season but not so early．The months of June and July provide the best leaf samples（样品），but you can find great leaf samples throughout the summer．To make a fall color collection，you have to collect the leaves in autumn．

    I have seen many beautiful fall color collections．

    When you choose leaves for your samples，try to choose leaves of about the same size and shape on the tree．Make sure you collect the entire（完整的） leaves．

    Remember，some leaves have only one blade（叶片） or leaflet（小叶）．Some leaves have a few or many leaflets．You must know these two kinds of leaves．Good leaf collections contain the entire leaves．

    You should dry the collected leaves carefully before putting them in a leaf press（压）．When you collect leaves in the field，you can put them between the pages of book to protect them．And then，press them as soon as possible before you take them from this book．Finally，you should write down each leaf's name and put them in a leaf press．

New App Helps People Remember Faces

    Large gatherings such as weddings and meetings can be socially Q flooded with people. Learning people's names only adds to the stress. A new facial-recognition app could come to the rescue, but experts suggest people should be careful while using it.

    The app, called SocialRecall, connects names with faces through smartphone cameras and facial recognition, avoiding the need for formal introductions. "It breaks down these social barriers we all have when meeting somebody, "says Barry Sandrew, who created the app and tested it at an event attended by about 1, 000 people.

    After receiving an invitation to download SocialRecall from an event organizer, the user is asked to take two selfies and sign in through social media. At the event, the app is active within a previously set geographical area. When a user points his or her phone camera at an attendee's face, the app identifies the person, displays the person's name, and links to his or her social media information. To protect Privacy, it recognizes only those who have agreed to use. And the app's creators say it automatically removes users' data after an event.

    Ann Cavoukian, a expert who runs the Privacy by Design Center of Excellence praises the app's creators for these protective measures. She added, however, that when people choose to share their personal information with the app, they should know that "there may be unexpected results down the road with that information being used in another situation that might come back to bite you."

    The start-up project has developed the app for people who suffer from prosopagnosia, or "face blindness, "a condition that prevents people from recognizing people they have met. To use this app, a person first receives an image of someone's face, from either the smartphone's camera or a photograph, and then tags it with a name. When the camera spots or recognizes that same face in real life, the previously entered information is displayed. The collected data are stored only on a user's phone, according to the team behind the app.