Food sometimes gets poisoned with harmful things. A person who eats such food can get an illness called food poisoning. Food poisoning is usually not serious, but some types are deadly. The symptoms of food poisoning usually begin within hours of eating the poisoned food. Fever is one of the most common symptoms.

Certain microorganisms(微生物)cause most types of food poisoning. Bacteria and other microorganisms can poison eggs, meat, vegetables, and many other foods. After entering the body, these tiny living things release(释放)poisons that make people sick.

Some chemicals can also cause food poisoning. They are often added to food while it is being grown, processed, or prepared. For example, many farmers spray chemicals on crops to kill weeds and insects. Some people may have a bad reaction to those chemicals when they eat the crops.

Some plants and animals contain natural poisons that are harmful to people. These include certain kinds of seafood, grains, nuts, seeds, beans, and mushrooms.

When people handle food properly, the risk of food poisoning is very small. Microorganisms multiply rapidly in dirty places and in warm temperatures. This means that people should never touch food with dirty hands or put food on unwashed surfaces. Food should be kept in a refrigerator to stop microorganisms from growing. Meat needs to be cooked thoroughly to kill any dangerous microorganisms. People should also wash food covered with chemicals before eating it. Finally, people should not eat wild mushrooms or other foods that grow in the wild. Some of these foods may contain natural materials that are poisonous to humans. In addition, some types of fish can be poisonous.

Most people recover from food poisoning after a few days of resting and drinking extra water. If people eat natural poisons, they must go to the hospital right away to have their stomachs emptied.

    According to researchers at Yale University’s Infant Cognition Center, babies can actually tell good from evil, even as young as three months old.

    Puppets are used to demonstrate good and bad behavior. In one case, a puppet is struggling to open a box. Another puppet, the “good” puppet, helps it open the box, while another, the “bad” puppet, shuts the box on purpose.

    More than 80% of the times that experiment is conducted, babies will select the “good” puppet when presented with both puppets and given the chance to choose either one.

    Humans are born with a sense of good and evil, according to Paul Bloom, Yale’s Brooks and Suzanne Ragen professor of psychology.

    “We are naturally moral beings, but our environment can enhance—or sadly, weaken—this innate moral sense,” Bloom said.

    So now I’m wondering if, during those months when I thought my babies had no idea about the world around them, I did anything I should not have done.

    Lyz Lenz, mom of a nearly 3-year-old daughter and 7-month-old son, wonders the same thing.

    “After the birth of my daughter, I watched all of ‘Damages’, a show where Glenn Close plays an evil lawyer,” she said.

    Many women I chatted with over e-mail or on Facebook weren’t really surprised to learn there’s much more going on in the brains of our littlest ones.

    Jessica McFadden, founder of the blog A Parent in America and Mother of Three, remembers when her daughter Alice was 4 months old.

    “She would babble (talk quickly in a way that is hard to understand) worriedly in front of the large family photo hanging in our home,” said McFadden. The photo was taken before her daughter was born and included everyone in the family—except her.

    “She truly seemed put out that she was not in the picture! When the photo was replaced with a new one including her, she smiled, waved her hands and would happily look at it each time she passed it,” she said.

Most episodes of absent-mindedness—forgetting where you left something or wondering why you just entered a room—are caused by a simple lack of attention, says Schacter.“You’re supposed to remember something, but you haven’t encoded it deeply.”

Encoding，Schacter explains，is a special way of paying attention to an event that has a major impact on recalling it later. Failure to encode properly can create an annoying situation. If you put your mobile phone in a pocket, for example, and don’t pay attention to what you did because you’re involved in a conversation, you’ll probably forget that the phone is in the jacket now hanging in your wardrobe(衣柜). “Your memory itself isn’t failing you, ” says Schacter. “Rather, you didn’t give your memory system the information it needed. ”

Lack of interest can also lead to absent-mindedness. “A man who recites sports statistics from 30 years ago, ”says Zelinski, “may not remember to drop a letter in the mailbox.” Women have slightly better memory than men, possibly because they are more interested in what’s happening around them, and memory relies on just that.

Visual cues(提示) can help prevent absent-mindedness, says Schacter. “But be sure the cue is clear and available, ”he cautions. If you want to remember to take a medication with lunch, put the pill bottle on the kitchen table—don’t leave it in the medicine chest and write yourself a note that you keep in a pocket.

We all know the feeling: looking at the computer screen, pretending to be interested in our homework, even though we really feel bored. But such feelings may soon be at an end, says Dr. Harry Witchel, head of the Essex Medical School. He believes that computers of the future will notice when people feel bored and even take action to stop it.

Before you get concerned, the machine won’t be reading your mind. It will be observing the many movements you make while using a computer. It’s not interested in the big movements needed to use the machine一 like moving a mouse or touching a screen — but small, barely noticeable movements like closing your eyes，moving in your seat or rubbing your face. Witchel calls these “boredom movements" and says they show how interested the person is in what they are reading or watching. The higher the interest level, the less movement!

To test his theory, Witchel invited 27 people to perform various computer-based tasks. The activities ranged from playing online games (an interesting task) to reading documents like government laws that most people would find boring.

A special video camera followed the participants’ movements as they completed each task. Just as the researcher expected, the “boredom movements" greatly decreased, by as much as 42%，when the subjects were very interested in what they were reading or seeing.

Fortunately, DrWitchel isn’t planning to use his results to create machines that report students who are not paying attention at school. Instead, he wants “movement sensing” technology to be built into future computers in order to improve students' computer-based learning experience.

The scientist says that by measuring the students' interest level as they work, educators will be able to adjust their materials in real-time to keep students focused. Witchel also believes that the technology can provide filmmakers with honest audience opinions and in the future, help to develop more intelligent robots.

A book review tells not only what a book is about，but also how successful it is at what it is trying to do.Professors often assign book reviews as practice in careful analytical(分析的)reading.

As a reviewer，you bring together the two strands of accurate，analytical reading and strong，personal response when you indicate (指出)what the book is about and what it might mean to a reader (by explaining what it meant to you)．In other words，reviewers answer not only the WHAT but the SO WHAT question about a book.Thus，in writing a review，you combine the skills of describing what is on the page，analyzing how the book tried to achieve its purpose，and expressing your own reactions.

Most book reviews start with a heading that includes all the basic information about the book，like：

Title.

Author.

Place of publication，publisher，date of publication.

Number of pages.

Like most pieces of writing，the review usually begins with an introduction that lets your readers know what the review will say.The first paragraph usually includes the author and title again，so your readers donˈt have to look up to find this information.You should also include a very brief description of the contents of the book，the purpose or audience for the book，and your reaction and evaluation.

Then you move into a section of background information that helps place the book in context and discusses how to judge the book.Next，you should give a summary of the main points，quoting (引用)and explaining key phrases from the author.Finally，you get to the heart of your review—your evaluation of the book.In this section，you might discuss some of the following issues：

•How well the book has achieved its goal.

•What possibilities are suggested by the book.

•What the book has left out.

•How the book compares with others on the subject.

•What specific points are not convincing.

•What personal experiences youˈve had related to the subject.

It is important to use labels to carefully distinguish your views from the authorˈs，so that you donˈt confuse your reader.^①

Then，like other essays，you can end with a direct comment on the book，and tie together issues raised in the review in a conclusion.

There is，of course，no set form，but a general rule is that the first one-half to two-thirds of the review should summarize the authorˈs main ideas and at least one-third should evaluate the book.

Language as a System of Symbols

    Of all systems of symbols (符号), language is the most highly developed. It has been pointed out that human beings, by agreement, can make anything stand for anything. Human beings have agreed, in the course of centuries of mutual(相互的) dependency, to let the various noises that they can produce with their lungs, throats, tongues, teeth, and lips systematically stand for certain happenings in their nervous systems. We call that system of agreements language.

    There is no necessary connection between the symbol and that which it stands for. Just as social positions can be symbolized by feathers worn on the head, by gold on the watch chain, or by a thousand other things according to the culture we live in,so the fact of being hungry can be symbolized by a thousand different noises according to the culture we live in.

    However obvious these facts may appear at first glance, they are actually not so obvious as they seem except when we take special pains to think about the subject. Symbols and the things they stand for are independent of each other, yet we all have a way of feeling as if, and sometimes acting as if, there were necessary connections.

    For example, here are people who feel that foreign languages are unreasonable by nature：foreigners have such funny names for things, and why can't they call things by their right names? This feeling exhibits itself most strongly in those English and American tourists who seem to believe that they can make the natives of any country understand English if they shout loud enough. Like the little boy who is reported to have said： "Pigs are called pigs because they are such dirty animals,” they feel that the symbol is inherently (内在地) connected in some way with the things symbolized.