To help the environment, many Americans have made the change from paper and plastic bags to reusable shopping bags.But a report by a Florida newspaper says that reusable shopping bags sold by some supermarkets have high levels of lead(铅), which can be dangerous to humans, especially young children.Now, there's a call for a rethink about the use of reusable shopping bags.

     “When our families go to the store looking for safe and healthy foods, the last thing they should be worrying about is a bag，”Charles Schumer, a government official said.“Quick and complete research will allow everyone to make right decisions.”

    The newspaper bought more than a dozen bags sold at Publix supermarkets from Florida supermarkets to test them for lead.The results showed that certain bags had lead levels that worried health officials.Some bags had enough lead in them to be considered dangerous waste if people were to throw the bags out with other rubbish.Lead in the bags is not likely to move onto food.But over time, paint (油漆) on the bags can break off and the bags can wear out.When this happens, lead can be freed.

    The affected (受影响的) bags were found in Florida.But Publix has more than 1，000 stores across America.Publix says that its bags don't break any laws about lead levels, but that they have asked the makers of the bags to reduce(降低) the lead levels in them.

    The bags with the highest levels of lead had beautiful designs and many pictures.Plain reusable bags without them are found to have little lead.People worried about lead levels in reusable bags can turn to cloth.Paper bags are also a good choice, since paper can be reused.

    Have you ever had the following experience? You have been given the task of organizing a conference, which includes a must-do list about a mile long. There is the conference site, the guest list, the materials, the technology and even the food and drink to think about and plan. If you are beginning to feel the stress, slow down and take a breath. {#blank#}1{#/blank#}.

    Write down your goals. You will need to clearly define what you hope to accomplish with this conference because this will shape the rest of your decisions.  {#blank#}2{#/blank#}.

    Develop your budget.  {#blank#}3{#/blank#}. Then break that budget into different parts such as conference site, materials and speakers' fees. Stick to your budget, and make sure your assistants are keeping their monetary limits as well.

     {#blank#}4{#/blank#}. When searching for locations, keep in mind the number of participants, the convenience of the location, parking and closeness to public transportation, airports and hotels. Your goal in finding a place to hold the conference should be making it as easy as possible for participants to attend.

    Seek help from the staff of the conference site. If you have chosen a site that is known for holding conferences, you can seek help from the staff there as organizing meeting is what they do every day.  {#blank#}5{#/blank#}. They should be able to answer any questions or concern and provide advice when needed.

    Of course, full preparations also include a walk-through. Go to the site and meet with the staff the day before to be certain that everything is in place and to take care of any small details.

  A. Decide on a schedule for the meeting

  B. Choose your conference site

  C. Read the following skills to figure out how to organize a conference

  D. Knowing what you want to achieve eases the stress of moving forward

  E. Make full use of this important resource

  F. You can do nothing without knowing how much money you have to spend

  G. Seek help from your colleagues to support every aspect of the meeting

Do you believe that things are connected for no scientific reason at all? For example, do you avoid saying the word "four" to avoid bad luck? If so, you have a superstition (迷信). And you're not alone – all kinds of people have them.

For example, Portugal's soccer superstar Cristiano Ronaldo always steps onto the pitch (球场) with his right foot first, according to The Telegraph. And sports players are not alone in having superstitions. A visitor once asked the Nobel Prize winning scientist Niels Bohr whether he really believed that the horseshoe he'd hung at his country home was lucky. "Of course not," the Danish physicist said. "But I understand it's lucky whether you believe in it or not."

One recent study found that even scientists at MIT and other top US schools tended to look for a meaning in natural events, similar to the connection between stepping on the pitch and playing soccer well, according to The Atlantic. When the researchers gave the scientists little time to answer questions, they were twice as likely to agree with statements such as "Trees produce oxygen so that animals can breathe" as they were when they had more time to think about their reply.

It seems that fear can make people think differently in this way, too. In a British study, students imagined meeting a "witch" who said she would cast (施魔法) an evil spell(符咒) on them. About half said a scientist should not be worried about the spell. Yet each of them said that, personally, they wouldn't let the witch do it to them.

So why are so many of us superstitious? Well, it seems to be our way of dealing with the unknown. "Many people quite simply just want to believe," Brian Crank, a professor of psychology at Missouri Western State University, said in a 2008 interview. "The human brain is always trying to work out why things happen, and when the reason is not clear, we tend to make up some pretty bizarre (古怪的) explanations."

    And these explanations aren't completely unhelpful. In fact, superstitions can sometimes work and bring real luck, according to psychologists at the University of Cologne in Germany in the May 2010 issue of the journal Psychological Science. They found that believing in something can improve performance on a task like an exam.

    So, what about you? What superstitions do you follow to keep you safe and successful?

    Some inventions are so useful, but seem so simple, that we wonder why no one thought of them long ago. Post-it Notes, the pieces of paper that you can stick almost anywhere and then remove without leaving any sign that they are there, are an example of such an invention.

    Post-it Notes were invented about twenty years ago by Art Fry, a scientist at 3M Corporation. The idea for the product came from an upsetting experience he often had while singing in his church choir. Fry used pieces of paper as bookmarks to mark the places in his book of songs, but these bookmarks were always falling out. He knew he needed a bookmark that would stay where he put it, but that he could remove without damaging the pages.

    Around that time, Fry heard about a new adhesive(粘合剂) that a colleague, Dr. Spence Silver had created. This adhesive was special because it was sticky, but not too sticky. It was strong enough to hold papers together, but weak enough not to tear the paper when it was removed. Fry saw that the new adhesive could help solve his bookmark problem. One morning, Fry put some of the adhesive on the edge of a piece of paper. Just as he hoped, it made a perfect bookmark.

    A short time later, Fry realized that his new invention had even more uses than being a great bookmark. He came to this realization when he wrote a note on one of his new “bookmarks” and attached it to a report he was going to give to a colleague. Soon, co-workers were asking Fry for more sample of his invention so that they could use the new type of notes themselves.

    Fry and some other people at 3M believed so much in the new product that they persuaded the company to give away thousands of the sticky pieces of paper for trial use. When some salespeople at 3M went to offices and showed workers just how helpful the new type of notes could be, they immediately received many orders. As more and more people discovered how useful Post-it Notes could be, the product took off.

    Born in Detroit, Michigan, on January 10^th, 1928. Philip Levine was formally educated in the Detroit public school system. After graduation from university, Levine worked a number of industrial jobs, including the night work in factories, reading and writing poems in his off hours. In 1953, he studied at the University of Iowa. There, Levine met Robert Lowell and John Berryman, whom Levine called his “one great guide”.

    About writing poems, Levine wrote: “I believed even then that if I could change my experience into poems I would give it the value and honor that it did not begin to have on its own. I thought too that if I could write about it, I could come to understand it: I believed that if I could understand my life——or at least the part my work played in it——I could write it with some degree of joy, something obviously missing from my life.”

    Levine published (出版) his first collection of poems. On the Edge in 1961, followed by Not This Pig in 1968. Throughout his life Levine published many books of poems, winning many prizes. A review said: “Levine writes poems about the bravery of men, physical labor, simple pleasures and strong feelings, often set in working-class Detroit or in central California, where he worked or lived.”

    He taught for many years at California State University, Fresno and served as Distinguished Poet in Residence for the Creative Writing Program at New York University. After retiring from teaching, Levine divided his time between Brooklyn, New York, and Fresno, California, until his death on February 14^th, 2015. His final poem collection, The Last Shift, as well as a collection of essays (短文) and other writings, My Lost Poets: A Life in Poetry, were published in 2016.

    We're reading a book or opening an envelope when, all of a sudden, there's a sharp pain on our finger. You see a little bit of blood and realize you've just gotten a paper cut.

    Dr. Hayley Goldbach, a resident dermatologist at UCLA Health, spoke about why paper cuts are so jagged, how the element of surprise leaves us in more pain and how to make sure they heal quickly.

    Dr. Goldbach explained that one reason paper cuts hurt so much is where they occur: primarily on the finger. We have nerve endings all over the body," she said. "In places where there is refined movement and sensation--like the lips or tips of the fingers-they have a high density of nerve endings." These nerve endings are known as nociceptors and they send signals to the brain about things that could cause a break in the skin, such as extreme hot or cold temperatures and chemicals.

    Another reason why paper cuts hurt so much is that you're using your hands throughout the day meaning that the wound is constantly getting opened. "You often get paper cuts on the pad or the tip of the finger, different from where you'd get a knife cut," said Dr. Goldbach. "It's hard not to use your hands, so there's constant pressure on the wound without u chanee for it to heal."

    "The paper itself is another reason why these superficial cuts leave us in so much pain. Paper might look and seem smooth but, if you study it under a microscope, the edge is actually jagged." Paper is quite sharp jagged-it's a bit of serrated edge," said Dr. Goldbach."It cuts you pretty quickly before you have the chance to realize it."

    Additionally, paper cuts are quite shallow, which makes them even more annoying to deal with.

    Dr. Goldbach added that there are mental and emotional elements that cause paper cuts to hurt more than other cuts. "There's the psychological element of surprise, and it happens so quickly that you don't have time to withdraw your hand "she said" With some other injuries, you feel pressure so you have time to react."

    She also added that because we don't expect to hurt ourselves while working with paper, the surprise of cuts leaves us in further pain. "We tend to be careful with a knife-you're being careful on purpose: because you know there: s a danger, "said Dr Goldbach. While we are careful with knives, we are not so careful with paper.