When a leafy plant is under attack ，it doesn't sit quietly. Back in 1983, two scientists, Jack Schultz and Ian Baldwin,reported that young maple trees getting bitten by insects send out a particular smell that neighboring plants can get. These chemicals come from the injured parts of the plant and seem to be an alarm.What the plants pump through the air is a mixture of chemicals known as volatile organic compounds,VOCs for short.

Scientists have found that all kinds of plants give out VOCs when being attacked .It's a plant's way of crying out.But is anyone listening?Apparently.Because we can watch the neighbours react.

    Some plants pump out smelly chemicals to keep insects away.But others do double duty .They pump out perfumes designed to attract different insects who are natural enemies to the attackers. Once they arrive, the tables are turned. The attacker who was lunching now becomes lunch.

    In study after study,it appears that these chemical conversations help the neighbors .The damage is usually more serious on the first plant,but the neighbors ,relatively speaking ,stay safer because they heard the alarm and knew what to do.

Does this mean that plants talk to each other? Scientists don't know. Maybe the first plant just made a cry of pain or was sending a message to its own branches, and so, in effect, was talking to itself. Perhaps the neighbors just happened to “overhear” the cry. So information was exchanged, but it wasn't a true, intentional back and forth.

    Charles Darwin, over 150 years ago, imagined a world far busier, noisier and more intimate(亲密的) than the world we can see and hear. Our senses are weak. There's a whole lot going on.

    The winter vacation is just around the corner. With such a long holiday to spend, have you decided where to get yourself relaxed from the great pressure of school study? Our company specializes in civil tours. We take pride in offering you the best services and in providing you with a vacation that will be fondly remembered. The following places can be your unforgettable destinations in our country.

    A. The Australian Museum

    The Australian Museum has an international reputation in the fields of natural history and indigenous studies research and exhibitions. The museum was established in 1827 and is Australia's first museum of natural science and cultural artifacts.

    B. Sydney Olympic Park

    Home of the Best Games Ever and 2003 Rugby World, Sydney Olympic Park is a gold medal attraction and continues to serve as a major sport and social venue.

    Apart from its ultra-modern sport venues, Sydney Olympic Park is set in extensive parklands. Bicentennial Park, one of Sydney's most popular recreational areas, is criss-crossed with walking and bicycle tracks.

    C. Art Gallery of New South Wales

    Located within a short walking distance from Sydney's CBD, the Art Gallery of New South Wales is one of Australia's foremost art museums housing some of the finest works of art in the country.

    The Gallery has a rich and diverse collection including key works of the Heidelberg School and favorite modern Australian artists including Brett Whiteley and Margaret Preston, as well as permanent Australian, European, Asian, contemporary and photographic galleries.

    D. Koalas Park Sanctuary

    Koalas are on show every day. Shows are at 10:20 A.M., 11:20 A.M., 2:00 P.M., 3:00 P.M. where you can cuddle, feed, pat and have your photo taken with the Koalas. See free roaming Koalas as well, 10 acres of rainforest. Walk in and pat our kangaroos.

    The next time you go grocery shopping, try speaking to other customers. One summer day, I took a smile and a warm heart into a small store in Oregon and got far more than groceries.

    I love fresh produce(农产品) in the store, and not just for the amazing colors provided by summer's bounty (慷慨) or the chance to joy over new choices from other countries. It's also because I just love watching people pick their produce.

    The day I was there I found a sale on amazing cherry tomatoes—along with a woman in her late 70s. Despite the fact that we were strangers, we began to discuss apples. She noted a problem with the Pink Ladies. "They tasted like I was eating an unripe green apple from the tree," she said, twisting her face as if still tasting the sour apple.

    I wondered if this is something most of my generation can even remember doing. I surely do. I mentioned that I often could not resist the green yet tempting fruit swinging from an apple tree. This was the start for a series of discussions as we shopped-covering such topics as nutrition, new foods and the quality of produce.

    By this time a third woman had joined in our conversation. The three of us continued along, unexpected friends, chatting about family size and the troubles a mom might have serving healthful foods that please the whole family.

    Eventually we all went our separate ways, but in the dairy(奶制品) section I heard a small voice say, "I finally caught up with you." It was the first woman I'd talked to, extending a bag of apricots(杏) to me. "I don't know if your family will eat these," she added, "but they have a super deal on them."

    Again I was brought back to my childhood, when I also ate apricots straight from the tree. My mouth watered at the remembered flavor.

    The old lady didn't realize that she'd given me far more than produce. With that offering came a sense of community, a flashback to days when it was OK to talk to a stranger. She brought back memories of summer fruits right from the tree—and a feeling that somehow those apricots were a thank-you for sharing my time with her in a very unlikely place.

    Some of the world's most significant problems never hit headlines. One example comes from agriculture. Food riots（暴动）and hunger make news. But the trend lying behind these matters is rarely talked about. This is the decrease in the growth in production of some of the world's major crops. A new study by the University of Minnesota and McGill University in Montreal looks at where, and how far, this decline is occurring.

    The authors take a vast number of data points for the four most important crops: rice, wheat, corn and soyabeans. They find that on between 24% and 39% of all harvested areas, the improvement inproduction that took place before the 1980s slowed down in the 1990s and 2000s.

    There are two worrying features of the slowdown. One is that it has been particularly sharp in the world's most populous countries, India and China. Their ability to feed themselves has been an important source of relative stability both within the countries and on world food markets. That self-sufficiency (自给自足) cannot be taken for granted if productions continue to slow down.

    Second, production growth has been lower in wheat and rice than in corn and soyabeans. This is problematic because wheat and rice are more important as foods, accounting for around half of all calories consumed. Corn and soyabeans are more important as feed grains. The authors note that "we have preferentially focused our crop improvement efforts on feeding animals and cars rather than on crops that feed people and are the basis of food security in much of the world."

    The report also states the more optimistic findings of another new paper which suggests that the world will not have to dig up a lot more land for farming in order to feed 9 billion people in 2050, as the Food and Agriculture Organisation has argued.

    Instead, it says, thanks to slowing population growth, land currently ploughed（犁）up for crops might be able to revert (回返) to forest or wilderness. This could happen. The trouble is that the prediction assumes continued improvements in productions, which may not actually happen.

    A few years ago, bubble tea(奶茶) exploded as a popular drink for Internet foodies(吃货) everywhere. Many take this Taiwanese drink as a guilt-free snack similar to juice or a cup of coffee. After all, it has the word "tea" in it, so it has to be healthy…right?

    Not quite. Like coffee, bubble tea's ingredients(成分，配料) might not be so bad on their own, but when they're loaded with sweetener(甜味剂) and artificial flavor(人工香料), they lose their nutritional (营养的) value fast.

    It all starts with those "bubbles" found at the bottom of your drink, which are actually round pieces of tapioca(木薯淀粉). Called "tapioca pearls(珍珠)," they're actually made from a vegetable that grows in South America. And as it turns out, those little balls are loaded with sugar—and not the nutritious, fiber-rich(富含纤维) kinds found in whole grains(全麦类), either.

Cooking tapioca pearls only makes it worse. They're typically fried in hot water, along with even more added sugar, for up to three hours. By that point, these balls could have nearly 160 calories per ¼ cup.

    And don't even get us started on what comes in the extra syrups(糖浆). Thanks to all those processed(加工的) ingredients, the average bubble tea can easily reach 300 to 400 calories per cup!

    On top of being an unhealthy habit, bubble tea could even shorten your life. In 2012, a group of German researchers from the University Hospital Aachen reportedly found aspolychlorinated biphenyls, or PCBs, in tapioca ball samples. These cancer-causing chemicals have also been shown to have other bad effects on the immune(免疫), reproductive(生殖), and nervous systems.

    You might want to lay off your bubble tea addiction. Thankfully, we have a few choices for low-calorie, healthier drinks, instead.

    We all know what a brain is. A doctor will tell you that the brain is the organ of the body in the head. It controls our body's functions, movements, emotions and thoughts. But a brain can mean so much more.

    A brain can also simply be a smart person. If a person is called brainy, he is smart and intelligent. If a family has many children but one of them is super smart, you could say, "He's the brains in the family." And if you are the brains behind something, you are responsible for developing or organizing something. For example, Bill Gates is the brains behind Microsoft.

    Brain trust is a group of experts who give advice. Word experts say the phrase "brain trust" became popular when Franklin D. Roosevelt first ran for president in 1932. Several professors gave him advice on social and political issues（问题）facing the U.S. These professors were called his "brain trust".

    These ways we use the word "brain" all make sense. But other ways we use the word are not so easy to understand. For example, to understand the next brain expression, you first need to know the word "drain". As a verb, to drain means to remove something by letting it flew away. So a brain drain may sound like a disease where the brain flows out the ears. But, brain drain is when a country's most educated people leave their countries to live in another. The brains are, sort of, draining out of the country.

    However, if people are responsible for a great idea, you could say they brainstormed it. Here, brainstorm is not an act of weather. It is a process of thinking creatively about a complex topic. For example, business leaders may use brainstorming to create new products, and government leaders may brainstorm to solve problems.

    If people are brainwashed, it does not mean their brains are nice and clean. To brainwash means to make some accept new beliefs by using repeated pressure in a forceful or tricky way. Keep in mind that brainwash is never used in a positive way.