The world consumes hundreds of billions of single-use plastic bags each year. They are difficult to recycle, wasteful and damage the nature. Environmental activists want to ban plastic bags or—as many communities have done —charge a fee for them. But the plastic bag industry defends their use, saying people reuse plastic bags, and industry officials argue recycling is a matter of personal responsibility and should not be forced.

    City officials say New Yorkers use 5.2 billion plastic bags each year. They are offered free with nearly every supermarket, or convenience store purchase. Many people like them, even if they sometimes feel guilty about using them. But what happens to those bags after they've been used in a huge environmental problem. They are found on beaches. They are caught in trees. They are swallowed by marine life.

    Plastic bags are made of petroleum products and natural gas, and do not biodegrade (分解). And they are difficult to recycle. So New York City spends nearly $ 10 million dollars a year to send 100—thousand tons of plastic bags to landfills out of state.

    In Washington, D.C., a five percent charge on all single-use bags led to about a 60 percent reduction and in Los Angeles County in California , a 10 cent charge on single-use bags led to a 95 percent reduction. With a 10 cent charge on bags, customers are much more likely to stop and think about whether they need a bag or not. And that's really all that these laws are doing.

    In the mid-2000s, Waze Mobile co-founder Ehud Shabtai received a cutting-edge (尖端的) gift from girlfriend: a GPS. The expensive gift was supposed to be helpful. But straight out of the box, it was already out of date.

    Shabtai, a coding enthusiast, had an immediate reaction to reinvent. Shabtai's solution? To build an app. With 80 million monthly active users globally and nearly 400,000 superusers who function much like Wikipedia volunteer editors (editing maps rather than words), Waze Mobile caught the eye of Google as a revolutionary approach to navigation (导航).

    Acquired by Google in 2013, Waze's value mainly lies in its high rate of user involvement. Unlike traditional navigation apps that simply show directions, Waze asks its users to report accidents and other road conditions in real time, so other users can avoid the traffic by using an alternative route.

    The goal behind Waze's approach is an ambitious one: not just avoid traffic, but end it altogether. Waze is finding new ways to put its loyal and active user base to use to make that vision a reality, including a plan to make carpooling (拼车) cool.

    To be sure, traffic jams are troubling people all over the world. Waze has been quietly ahead of the game for some time. In 2013, when Waze was just a small digital-mapping business with limited resources it had something Google Maps and other competitors didn't: richer GPS guidance thanks to its stream of live traffic reports from users.

    These users were the basis of Shabtai's plan to solve for his GPS device's “silent” hardware: he grounded the app in software that could be perpetually updated by users, anywhere and anytime.

    Waze Carpool is going straight to the heart of traffic jams, trying to get more drivers off the road and into carpools. The app has already connected tens of thousands of rideseekers with drivers willing to ferry them along a shared route, and that trend could be the answer to a traffic-free future.

    Crown shyness(树冠羞避) is a mysterious natural phenomenon in which the crowns of some tree species do not touch each other, but get separated by a gap clearly visible from ground level. The effect usually occurs between trees of the same species, but has also been observed between trees of different species.

    There are many theories going around, most of which make sense, but no one has been able to prove without the shadow of a doubt why some trees avoid touching each other.

    In his 1955 book Growth Habits of the Eucalypts, Australian forester M.R. Jacobs writes that the growing tips of the trees are sensitive to abrasion(擦伤), which results in crown shyness phenomenon. This theory was also supported by Dr. Miguel Franco. Some experiments have shown that if trees displaying crown shyness are artificially prevented from swinging in the wind and touching each other, they gradually fill up the gaps between them.

    But while the above theory is arguably the most widespread, it's certainly not the only one. Some scientists have suggested that crown shyness is a mechanism to stop the spreading of leaf-eating insects. These pests have been known to work together and create structures that extend up to 10 cm off of tree branches in order to reach other plants, so the gaps are the trees' natural defense method.

    One Malaysian scholar studied many trees, but found no traces of abrasions, despite their clear crown shyness. Instead, he suggests that the growing tips of the trees were sensitive to light levels and stopped growing when they got too close to other trees. Plants are able to sense how close they are to other plants and in order to get more light, they give off some chemical element to stop other trees from growing too close.

    Whatever the reason, one thing is for sure: plants are more intelligent than people used to think.

    Since many of you are planning to study at a college or university in the future, you may be curious to know what your future study will be like. This is the question I want to discuss with you today.

    First, let's talk about what your weekly timetable will look like. No matter what your major may be, you can expect to spend between four and six hours a week for each class attending lecture. Lectures are usually in very large rooms because some courses such as Introduction to Sociology or Economics often have as many as two or three hundred students, especially at large universities. In lectures, it's very important for you to take notes on what the professor says because the information in a lecture is often different from that in your textbooks. Also, you can expect to have exam questions based on the lectures. So it isn't enough to just read your textbooks; you have to attend lectures as well. In a typical week, you will also have a couple of hours of discussion for every class you take. The discussion part is a small group meeting usually with fewer than thirty students where you can ask questions about the lectures, the reading, and the homework. In large universities, graduate students called teaching assistants, usually direct discussion parts

    If your major is chemistry, or physics, or another science, you'll also have to spend several hours a week in the lab doing experiments. This means that science majors spend more time in the classroom than non-science majors do. On the other hand, people who major in subjects like literature or history usually have to read and write more than science majors do.

One of the most important things in the world is friendship. In order to have friends, you have to be a friend. But how can you be a good friend at school?

Listen — Listen when they are talking. Don't say anything unless they ask you a question. Sometimes it's not necessary for you to have anything to say; they just need someone to talk to about their feelings.

Help them — If your friend is ever in need of something, be there to help them. You should try to put them first, but make sure you don't do everything they want you to do. Try to take an extra (额外的) pencil or pen with you to classes in case (以防) they forget one. Have a little extra money in your pocket in case they forget something they need.

Be there for them — Try to make something for your friend to help make them feel better in hard times. Making cards and encouraging them are among the nicest things you can do for a friend. Marilyn Monroe, a famous U.S. actor, once said, "I often make mistakes. Sometimes I am out of control. But if you can't stay with me at my worst, you are sure not to deserve (值得) to be with me at my best." Always remember this! If you don't want to stay with your friends when they're in hard times, then you don't deserve to be with them when they're having a good time!

______ — Try to make plans with your friends. Go shopping, go for ice cream, have a party, go to a movie and so on. Take time to know each other even better by doing something you both enjoy. By planning things together, you both can have a good time. And you'll remember these things when you're all old!

No matter which place you decide to visit in Spain, you'll find a beautiful beach waiting just for you. These popular beaches can meet the needs of people from all walks of life.

Cala de Algaiarens, Minorea

With soft golden sand and clear water, this beach is perfect for snorkeling (浅滩潜水) and visiting underwater caves. The beach belongs to a local man, so tourists have to pay a small entry fee. The waves here can sometimes be huge so the beach isn't safe for kids.

Cala Tarida, Ibiza

Besides the big music festivals and the exciting nightlife, Ibiza is home to some of the most beautiful beaches; one of them is Cala Tarida. Just relax on the white sand or go swimming in clear water. It is an ideal location to spend a sunny day if you are in Ibiza.

Beach of La Concha, San Sebastian

It has been called the best city beach not just in Spain, but also in Europe. It's so popular during the holidays that tourists have to struggle to get some space. Even though the beach is a 10- minute walk from the city, the white sand and the amzing clear waters do make the city a new world.

Sotavento, Canary Islands

As an ideal choice for travelers, Sotavento offers 17 miles of white sandy beach. It is blessed with strong water and winds, making it a paradise (天堂) for surfers and kite flyers. The beach also hosts the popular World Kite Surf Championship every August.