Recent research from the Pew Internet Project suggests that 90% of Americans aged from 12 to 17 use the Internet, and 51% of those teens use social networks. However, there are many possible problems with social networking sites and the teenagers who use them.

Apart from the social advantages, social networking sites can be used to record school research, develop artistic talents and experiment with other forms of subject creation. They provide a way to communicate with others who share the same interests and to get helpful advice on ongoing projects.
Along with these advantages come some dangers. For example, most social networking sites are open to all, especially MySpace, which is the most popular social network among teens in America. It means that they could be put in unpleasant and frightening situations.
A greater danger is that teens may become objects of the people with secret purposes. The secrecy of some social networking sites makes it easy for dangerous people to find young teens and invite them into dangerous conversations. It's easy for them to pretend as teens and draw children into dangerous real-world communication as well. Then further hurt might be on its way.
Another danger is identity stealing, which can happen when teens share too much information about their names, dates of birth and locations.
Therefore, it's very important to make sure teens are safe when they use social networks.
Many of the same rules that work for online chat work for these sites:
※Don't use your real name.
※ Don't give out personal information to people you don't know. A last name and a town are enough for a bad guy to find where you are.
※ Don't believe that people are who they say to be.
※ Immediately end any communication that makes you uncomfortable and report it to a parent.
Only if you are sure of your safety, can you enjoy the fun brought by social networking. Besides, trying to deal with all problems on your own can lead to terrible results. Remember, asking your parents or school officials for help doesn't mean you are unable to do anything but wiser than many others.

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    Would it surprise you to learn that, like animals, trees can communicate with each other and pass on their wealth to the next generation--their young trees?

    Suzanne Simard, forest ecologist at the University of British Columbia, explains how trees are much more complex than most of us ever imagined. Simard and her colleagues have made the major discovery that trees and plants really do communicate and interact with each other.

    Trees live on through their group work and support, passing around the resources such as nitrogen and carbon “depending on who needs it by miles of underground fungi（真菌） networks. This makes sure that all trees in the forest ecological system give and receive just the right amount to keep them all healthy. This system works in a very similar way to the networks of neurons（神经元） in our brains, and when one tree is cut down, it affects all.

Simard talks about "Mother Trees". These are the largest, oldest trees that rise above the forest, a concept explained in the movie Avatar. These “Mother Trees" are connected to all the other trees in the forest by this network of fungi, and may manage the resources of the whole trees and plants in the forest. She explains how these trees pass on the wealth to the next generation, transporting important resources to young trees so they may continue to grow. When humans cut down "Mother Trees" without paying attention to these highly complex "tree societies” or the networks on which they feed, we are losing the chances to save the whole forest.

    "We didn't take any notice of it,” Simard says sadly. “Mother Trees move nutrition into the young trees before dying, but we never give them a chance.” If we could send this message to the forestry industry, we could make a huge difference towards our environmental protection efforts for the future.

    This is a home of the future, a "smart home", where technology can do almost everything. Imagine we are in the year 2050, ①the computer wakes Tom up in themorning as usual. In front of him is a to-do list of the important events for the day, and it is provided by the computer too. According to Tom's request, the computer serves a list of possible dishes. All the dishes are nice.

    As Tom eats breakfast, the computer reminds him to reply to Lucy. Before Tom finishes his next bite, Lucy's computer receives the message. Then Tom goes to the supermarket. The store's system checks his car when he drives to the pickup area and greets him by name. "Good morning, Tom! Your order is in Case4. Thank you for shopping.'' When Tom removes his order from Case 4, all trades are completed automatically(自动地)over the information superhighway. That is, the money is electronically paid into the bank. Soon after arriving at the office, Tom reads another message from Lucy, telling him that she will go to dinner with him.

    The smart home can also do many other things:

    ◆Find things like keys and mobile phones.

    ◆②        (打开或关闭)machines and lights with your voice.

    ◆Clean your home from clothes to buildings automatically.

    ◆Record everything and everyone entering and leaving the house.

    ◆Take care of each member of the family, young or old.

    ③With the development of technology, the smart home will come true in the future. It is sure to play an important part in our life.

    The Vieira family moved to the United States in 1981. At that time, they decided to stop speaking Spanish at home and only speak English.  This was because they were now living in an English-speaking country.

    Now the Vieira children are adults, and they sometimes travel to Spain to visit their family and friends. But they can't communicate with them. Unfortunately this is common. When people move to new countries, they often leave their own customs and mother language behind. This is a mistake because there are many benefits to knowing more than one language.

    One advantage of speaking more than one language is that you can communicate directly with more people around the world. You do not have to depend on others to talk for you, so you're more independent (独立). People who know only one language must use others to help them communicate.

    Furthermore, speaking a second language also allows people to experience other cultures and customs more effectively. Local expressions, vocabulary, and even jokes can have a powerful effect on a person's understanding of another culture. So, knowing more than one language increases your knowledge of other cultures.

    Finally, having more multi-language speakers improves relationships between countries. If people from different countries can communicate well, the world can become closer. Countries will then have more respect for each other and better understand each other.

    The benefits of knowing more than one language are clear. In fact, there are no disadvantages. It is very sad that many people don't try to learn another language. It is even worse when people let themselves forget their mother language and become silenced.

    A new rubbish sorting system (垃圾分类系统) has been put into use in Fangchengyuan Community in Beijing. Local people not only sort their rubbish, but also put QR codes (二维码) on it.

    "When the rubbish is collected and the codes are scanned (扫描), I will get reward points to exchange for small gifts and even some money," one of the local people told reporters. "It's really creative and encouraging."

    This smart system has been carried out in 350 communities in Beijing. The capital of China has joined a list of cities in the country that take action to support rubbish sorting. For example, Shenzhen and Shanghai have made laws to punish people and organizations for not sorting rubbish correctly.

    China produces quite a lot of rubbish every year. Much of the rubbish is buried (填埋) in soil or burned without being sorted. Landfills (填埋场) take up a lot of land and have a risk of polluting the soil and water nearby. And burning rubbish can produce harmful gases. Through rubbish sorting, we can reduce the use of landfills and air pollution.

    What's more, rubbish sorting saves resources, which could bring economic benefits (经济利益). For example, a ton of waste paper can be reused to make about 850kg of paper, saving 17 trees and 50 percent of water. Because of their benefits, some countries have developed successfully sorting systems.

    In Australia, every family is provided with three rubbish bins—the red lid (盖子) bin for "general waste" like food and plastic bags, the yellow lid bin for "recyclable (可回收利用的) waste" like steel and glass, and the green lid bin for "green waste", such as grass and leaves. On the street, the bins are printed with pictures of the things that are allowed inside. It makes recycling quite easy.