People have smoked cigarettes for a long time now. The tobacco which is used to make cigarettes was first grown in what is now part of the United States. Christopher Columbus, who discovered America, saw the Indians smoking. Soon the dried leaves were transported to Europe. In the late 1800s, the Turks made cigarettes popular.

    Cigarette smoke contains at least two harmful substances, tar and nicotine. Tar, which forms as the tobacco burns, damages the lungs and therefore affects breathing. Nicotine, which is found in the leaves, causes the heart to beat faster and increases the breathing rate. Nicotine in large can kill a person by stopping a person's breathing muscles. Smokers usually take in small amounts that the body can quickly break down.

    Nicotine can make new smokers feel dizzy(头晕) or sick to their stomachs. The heart rate for young smokers increases 2 to 3 beats per minute. Nicotine also lowers skin temperature and reduces blood flow in the legs and feet. It plays an important role in increasing smokers' risk of heart disease and stroke.

    Smoking cigarettes is dangerous. Cigarette smoking was the cause of lung cancer and several other deadly diseases.

    Pound for pound, healthy food is cheaper than junk food, according to a new research from the U. K.

    The Institute of Economic Affairs found that the average cost for a “wide range” of healthy foods was about £ 2 per kilogram, compared with £ 3 a kilogram for less-healthy products such as processed and ready-made foods.

Still, study after study finds that cost is often a barrier when it comes to healthy eating. Convenience drives consumers to care about habits more than prices, the U. K. study concluded. Taste and convenience often play a larger role in people's food choices than price or nutritional quality.

    “Processed foods are extremely expensive, especially when it comes to the nutrient value. Some of the healthiest, most inexpensive foods aren't so attractive. Beans cost next to nothing, especially when bought dry and in great amounts. They take time and some skills to prepare. ” said Ciara Foy, a nutritionist.

    Instead, busy parents reach for the chicken. “You might be getting something that has enough calories to fill you up but you're actually not getting any nutrients, so your body's going to keep wanting more and more food,” said Foy. “And that's why in North America we, re overfed and undernourished (营养不良的).”

    Makers tend to try to promote their product based on perceived health benefits, which makes consumers confused at times with what is a healthy product and how much you should pay for those benefits. The most expensive items, healthy or not, are the ones that end up in the trash. “A lot of people waste a lot of food,” Foy said. It's estimated that more than $ 30 billion of food is wasted in Canada every year. Foy recommends taking a look in your fridge to see what needs to be used up when planning for the next night's meals. “If you actually cut down on the waste you'll find that you can afford healthy food,” Foy said.

    To be honest, I do not know Sybrina Fulton. Nor can I claim to understand the depth of her pain. Yet, we share a deep connection. A common feature experienced by those women who face the challenge of raising a Black male child in a nation that far too often views Black male bodies through fear. You see, Ms. Fulton is living my nightmare (噩梦). A constant worry that has stayed in the back of my mind since the birth of my eldest son, some sixteen years ago.

    Through the years, I have witnessed the world's reaction to my son evolve as he has grown from a small boy to a young man. In his early years, his easy smile and lovable character were nothing less than magnetic (有磁性的). Complete strangers would approach him in the street, draw him into conversation, and find themselves easily struck by his lively spirit. Even at that time I worried, how would my son react when in the years to come some of those who found themselves so impressed by this cute, intelligent boy, might grasp their purse tighter as he walked by.

    Over the years I have sought to protect his spirit from the hurt that comes from undeserved hatred. I have also sought to arm him with the knowledge that could one day save his life. He knows, for example, that if he is ever pulled over by the police, that he is to keep both hands on the wheel at all times and only reach for his license when the officer is specifically observing his actions. He knows, even in less threatening situations, that rough play and loud interactions with his buddies of any color will be viewed very differently when he does it, than when his white friends display the very same behavior. Still, the truth of the matter is, no amount of advice or voiceless behavior overcomes the physical, immovable fact of the color of his skin. His intelligence, easy smile, and lovable character won't protect him from unfounded assumptions of criminality.

    What makes the Trayvon Martin travesty (歪曲) of justice so painful to me, personally, is the knowledge that Trayvon's mother loved her baby no less than I love mine. The various pictures of moments throughout a happy childhood that have now found a home on nationwide newscasts provides clear evidence of that. Yet no amount of love and care, and no words of advice could have saved her son from the cruel killing he faced at the hands of a self-appointed neighborhood watch-dog. And perhaps even worse, nothing could have prepared her for the inhuman way her son has been treated by officials even in death. To think for three long days, his parents searched for him while officials failed to inform them of his fate and instead, performed drug and alcohol tests on his lifeless body, while failing to do the same for his attacker—the only one of the two who indeed had a criminal past is frankly, unforgivable. To know that the words of her son's killer were given more weight than eye-witnesses and taped evidence of her child's screams and eventual death must be heartbreaking. But to also have to live with the fact that his attacker still breathes free while her son lays buried underground is certainly more than any sorrowful parent should have to endure (忍受).

    It is this type of pain that is not unfamiliar to the Black experience in America, for this is the Black mothers' burden. A burden we have endured for centuries. Yet, there is still the rightful expectation, that in modern-day America, the wheels of justice would not be stopped.

    So today, it is my hope that Trayvon's mother, father, family and friends can take some comfort in the fact that millions of Americans of every color stand with them in their fight for justice. This is a burden no family should have to endure alone.

    We will not give up. We will not forget. We will continue the fight until justice is done.

    Your local grocery store is a psychological minefield (布雷区), where even the bananas are ripe with mystery.

    ⒈Southpaws (左撇子) have an invisible advantage

    You've probably seen that stores keep go-to items produce, meats, dairy on the outer edge. But did you notice that most of them are set up to make you run counterclockwise (逆时针)? Ninety percent of us are right-handed, so we buy more when it's counterclockwise. You'll also often find the dairy section in the back-left corner: Because dairy is likely on your list, stores make sure you take the longest route to get there. In fairness, it's also a more convenient place to put a fridge.

    ⒉Everything is in its place

    It's safe to say that nothing you see on a shelf is there by chance. The cookies on sale at the end of a passage are likely the result of smart product placement. More expensive items are usually placed at an adult's eye level, while colorful treats and other products for kids are positioned lower to catch the attention of children.

    ⒊Time goes by so slowly

    Stores rarely have windows or clocks. With no reference to the outside world, customers can easily lose track of how long they've been there so that they can buy more. Grocery stores may use another trick to control your sense of time: small floor tiles (瓷砖).

    We've all heard the saying: practice makes prefect! In other words, acquiring skills takes time and effort. But how exactly does one go about learning a complex subject such as tennis, calculus, or even how to play the violin? An age-old answer is: practice one skill at a time. A beginning pianist might rehearse scales(音阶) before chords(和弦). A young tennis player practices the forehand before the backhand. Learning researchers call this “blocking”， and because it is common and easy to schedule, blocking is dominant in schools, training programs, and other settings.

    However another strategy promises improved results. Enter “interleaving”， a largely unheard-of technique that is catching the attention of  cognitive(认知) psychologists and neuroscientists. Blocking involves practicing one skill at a time before the next (for example, “skill A” before “skill B” and so on, forming the pattern “AAABBBCCC”), while in interleaving one mixes practice on several related skills together (forming for example the pattern “ABCABCABC”).

    Over the past four decades, a small but growing body of research has found that interleaving often outperforms blocking for a variety of subjects, including sports and category learning. Yet there have been almost no studies of the technique in unplanned, real world settings-until recently. New research in schools finds that interleaving produces dramatic and long-lasting benefits for an essential skill: math. Not only does this finding have the potential to transform how math is taught, it may also change how people learn more generally.

    Researches are now working to understand why interleaving produces such impressive results. One important explanation is that it improves the brain's ability to tell apart between concepts. With blocking, once you know what solution to use, or movement to do, the hard part is over. With interleaving, each practice attempt is different from the last, so rote(死记硬背) responses don't work. Instead, your brain must continuously focus on searching for different solutions. That process can improve your ability to learn critical features of skills and concepts, which then better enables you to select and produce the correct response.

    A second explanation is that interleaving strengthens memory associations. With blocking, a single strategy，temporarily held in short-term memory, is sufficient. That's not the case with interleaving-the correct solution changes from one practice attempt to the next. As a result, your brain is continually engaged at regaining different responses and bringing them into short-term memory. Repeating that process can strengthen neural connections between different tasks and correct responses, which improves learning.

    Both of these accounts imply that increased effort during training, either to discriminate correct responses or to strengthen them, is needed when interleaving is used. This corresponds to a potential drawback of the technique, namely that the learning process often feels more gradual and difficult in the beginning. However, that added effort can have better, longer-lasting results.

I first came across the concept of pay­what­you­can cafés last summer in Boone, N. C. , where I ate at F. A. R. M (Feed All Regardless of Means) Café. You can volunteer to earn your meal, pay the suggested price ($10) or less, or you can overpay—paying it forward for a future customer's meal. My only regret after eating there was not having a chance to give my time. So as soon as Healthy World Café opened in York in April, I signed up for a volunteer shift(轮班).

F. A. R. M and Healthy World are part of a growing trend of community cafés. In 2003, Denise Cerreta opened the first in Salt Lake City. Cerreta now runs the One World Everybody Eats Foundation, helping others copy her pay­what­you­can model.

"I think the community café is truly a hand up, not a handout," Cerreta said. She acknowledged that soup kitchens(施粥所) have a place in society, but people typically don't feel good about going there.

"One of the values of the community café is that we have another approach," she said. "Everyone eats here, no one needs to know whether you volunteered, overpaid or underpaid. "

The successful cafés not only address hunger and food insecurity but also become necessary parts of their neighborhood—whether it's a place to learn skills or hear live music. Some teach cooking to seniors; some offer free used books. Eating or working there is a reminder that we are all in this world together.

My 10 am～1pm shift at World Healthy Café began with the café manager—one of the two paid staff members. Our volunteer crew wasn't the most orderly, but we managed to prepare and serve meals with a lot of laughs in between. At the end of my shift, I ordered my earned meal at the counter, together with other volunteers. After lunch, I walked out the door, with a handful of new friends, music in my head and a satisfied belly and heart.