The wonderful experiment I am going to introduce proves that air is just all around and that it presses down upon us. Air pressure is a wonderful force. When you swim underwater, you can feel water push down your body. The air all around you does the same. However, your body is so used to it that you do not notice this. The pressure is caused by a layer of air called the atmosphere. This layer surrounds the Earth, extending to about five kilometers above the Earth's surface.

    The following experiment is an easy one that you can do at home. But make sure that you are supervised, because you will need to use matches. Now for the experiment！

    What you need:

·A hard-boiled egg without the shell

·A bottle with a neck slightly smaller than the egg

·A piece of paper

·A match

Method:

1） Check that the paper will sit firmly on the neck of the bottle.

2） Tear the paper into strips and put the strips into the bottle.

3） Light the paper by dropping a burning match into the bottle.

4）Quickly sit the egg on the neck of the bottle.

Result:

    Astonishingly, the egg will be sucked into the bottle. Your friends will be amazed when you show them the experiment. But be careful when you handle matches.

    Why it happened

    As the paper burns, it needs oxygen and uses up the oxygen（air）in the bottle. The egg acts as a seal in the neck of the bottle, so no more air can get inside. This reduces the air pressure inside the bottle. The air pressure must equalize, so more air from outside must enter the bottle. The outside air pressure against the egg and then the egg is pushed into the bottle! This proves that air is all around and that it is pressing down on it.

    An autonomous vehicle designed for making local commerce deliveries was unveiled by Nuro. The vehicle is about the height of an SW but far narrower than a typical car. The electric car features four exterior compartments (暗格) — two on each side — to hold separate deliveries. Each compartment can be tailored to a specific use, such as cooking a pizza or refrigerating a package.

    “We can use self-driving technology to deliver anything, anytime, anywhere for basically all local goods and services,” Nuro co-founder Dave Ferguson said. “Consumers used to be okay with two-week paid shipping. It became two-week free delivery, followed by one week, two days, and the same day. Now same-day delivery isn't fast enough for some customers.”

    Nuro isn't alone in building robots for local commerce deliveries. Earlier this month, Toyota, a Japanese car company, unveiled a concept vehicle that could be used for package delivery. A handful of startups — including Starship Technologies, Marble and Dispatch — are testing small robots for deliveries on sidewalks.

    Nuro's vehicle will likely face legal hurdles. Fully autonomous vehicles without a test driver aren't legal in California today, and many companies have shifted testing to states where regulators are more welcoming of autonomous vehicles, such as Arizona.

    Nuro expects to face fewer challenges because it doesn't carry passengers. Nuro's narrow size may also be helpful when navigating streets and avoiding pedestrians. The vehicle isn't equipped with any special features to communicate with pedestrians or other road users. Some companies have tested and patented solutions such as digital screens that signal the car's next move. Ferguson said his team conducted studies and found that such techniques could confuse people. Nuro believes it's better to make sure the car performs predictably, so that human drivers know what to expect from it.

    “We feel by creating this new technology that's going to enable this last mile delivery, we're going to be creating new markets and doing things that previously weren't possible,” Ferguson said. “This is not swapping out Jobs with robots. It's creating new markets. There will definitely be new employment opportunities.”

    Many people believe high heels(E)make women look good. It seems that the organisers of the Cannes Film Festival reportedly stopped women in low-heeled shoes from walking the red carpet. But all this charm comes at a cost, wearing heels over 10em high can damage your feel.

    A study by Hanseo University in South Korea suggests that continuous wearing makes women run the risk of getting hurt, and makes them easy to lose their balance, A total of 40 women who wear high heels at least three times a week took part in the study, The strength of their feet was measured regularly, researchers found that two of the four main muscles became stronger after a period of between one and three years, This created an imbalance in their feet, Dr Yong Seok Jee from Hanseo University says that the habit of wearing heels can result in feet out of shape, back pain and unhealthy walking patterns He suggests that women limit the use of these kinds of shoes and exercise their foot muscles properly.

    High heels are considered by some people to be female, but in fact the fashion started with men's feet. These shoes were a form of riding footwear, and were seen on the feet of 17th century Persian soldiers, Elizabeth Semmelhack of the Bata Shoe Museum in Toronto says: “When the soldier stood up in his stirrups (马镫), the heel helped him keep balance so that he could shoot more effectively.

    Before becoming a main part of modern women's clothing, high heels were used by Louis XIV of France. These shoes were status (身份) symbols Lets face it-nothing shows off status like uncomfortable, expensive and impractical clothing. They say the wearer doesn't have to work in fields or walk very far.

    There are a couple different things that make ramen noodles an unhealthy choice. There's not much to these provision packets besides salt and carbohydrates. While those certainly get thrown around quite a bit as “bad-for-you” comments, you may not know how they actually harm your body. Firstly, there's the fact that most instant ramen servings contain over 1100 milligrams of sodium-that's approaching half of the maximum you should eat per day. When you take in that much sodium in a single sitting, your body overcompensates by holding more water. This can cause temporary water weight gain, leaving you feeling bloated(肿胀)and lacking in energy.

    But while you may feel bloated, chances are you won't feel full. Since the ramen contains lots of refined carbohydrates with virtually no protein or fiber, it's essentially the very definition of empty calories. And you've probably heard the song-and-dance about refined carbs; eating too much can lead your blood sugar to increase and then decrease, leaving you hungry and ready to eat again-which leads to weight gain.

    And, perhaps most upsetting of all, this quick-and-easy meal may stay with you much longer than you realize. Massachusetts General Hospital's Dr. Braden Kuo used a pill-sized camera to record the digestive tracts of volunteers who ate processed ramen noodles as well as fresh ones. With a video, Dr. Kuo was able to show that, after two hours when the fresh noodles were long gone, the ramen noodles were still there in the intestines.

    Doctors do know that years of eating the instant packets are linked to poor health. Another study, this one by the Harvard School of Public Health, assessed the long-term consequences of ramen consumption in South Korea, where it's a major course. They found that subjects, women in particular, who ate instant noodles at least twice a week had a 68 percent higher risk of diabetes and heart disease-than subjects who ate a more consistently natural diet.

    In short, eating ramen once in a while won't damage your health-as is true with most processed foods. But it's not something you should make a habit of-for your stomach and heart's sake.

    Teenagers who talk on the phone a lot and hold their cell phones up to their right ears score worse on one type of memory test. That's the finding of a new study. That memory damage might be one side-effect of the radiation that phones use to keep us connected while we're on the go.

    Nearly 700 Swiss teens took part in a test of figural memory. This type helps us recall abstract symbols and shapes, explains Milena Foerster. She's an epidemiologist(流行病学家). She worked on the study as part of a team while Foerster was at the Swiss Tropical and Public Health Institute in Basel, Switzerland. Teens participated memory tests twjce, one year apart. Each time, they had one minute to memorize 13 pairs of abstract shapes. Then they were shown one item from each pair and asked to match it with one of five choices.

    The study volunteers also took a test of verbal memory. That's the ability to remember words. The two memory tests are parts of an intelligence test.

    The researchers also surveyed the teens on how they use mobile phones. And they got call records from phone companies. The researchers used those records to estimate how long the teens were using their phones. This allowed the researchers to calculate how big a radiation exposure each person could have gotten while talking.

    All cell phones give off energy in the form of radio frequency electromagnetic fields, or RF-EMFs. Radio and TV broadcasts also use this type of energy. So do microwave ovens and some other gadgets(配件).

    "For a phone, that energy carries information, in the form of calls or texts between phones and cell phone towers. That radiation also can travel into people's bodies as they use their phones. And some of its energy can be absorbed by the body. So far, scientists have not shown that radiation from phones causes harm," says the Federal

    Communications Commission. Research is ongoing, this agency notes.

    If English means endless new words, difficult grammar and sometimes strange pronunciation, you are wrong. Haven't you noticed that you have become smarter since you started to learn a language?

    According to a new study by a British university, learning a second language can lead to an increase in your brain power. Researchers found that learning other languages changes grey matter. This is the area of the brain which processes information. It is similar to the way that exercise builds muscles.

    The study also found the effect is greater when the younger people learn a second language. A team led by Dr. Andrea Mechelli, from University College London, took a group of Britons who only spoke English. They were compared with a group of "early bilinguals" who had learnt a second language before the age of five, as well as a number of later learners.

    Scans showed that grey matter density (密度) in the brain was greater in bilinguals than in people without a second language. But the longer a person waited before mastering a new language, the smaller the difference.

    "Our findings suggest that the structure of the brain is changed by the experience of learning a second language," said the scientists.

    It means that the change itself increases the ability to learn.

    Professor Dylan Vaughan Jones of the University of Wales, has researched the link between bilingualism and maths skills. "Having two languages gives you two windows on the world and makes the brain more flexible (灵活的)," he said. "You are actually going beyond language and have a better understanding of different ideas."

    The findings were matched in a study of native Italian speakers who had learned English as a second language between the ages of two and thirty-four. Reading, writing, and comprehension were all tested. The results showed that the younger they started to learn, the better. "Studying a language means you get an entrance to another world," explained the scientists.