Many animals recognize their food because they see it.So do humans.When you see an apple or a piece of chocolate you know that these are things you can eat.You can also use other senses when you choose your food.You may like it because if smells good or because it tastes good.You may dislike sonic types of food because they do not look,smell or taste very nice.Different animals use different senses to find and choose their food.A few animals depend on only one or their senses,while most animals use more than one sense.

    Although there are many different types of food,some animals spend their lives eating only one type.The giant panda eats only one particular type of bamboo.Other animals eat only one type of food even when given the choice. A kind of white butterfly will stay on the leaves of a cabbage,even though there are plenty of other vegetables in the garden.However,most animals have a more varied diet.The bear eats fruits and fish.The fox eats small animals,birds and fruits.The diet of these animals will be different depending on the season.

    Humans have a very varied（广泛的）diet.We often eat food because we like it and not because it is good for us. In countries such as France and Britain,people eat foods with too much sugar.This makes them overweight,which is bad for their health.Eating too much red meat and animal products,such as butter,can also be bad for the health. Choosing the right food,therefore,has become an area of study in modern life.

    Author Norman Mailer published an essay in which he declared the graffiti(涂鸦) of the New York subway to be "The Great Art of the 70s". But what happened to the artists and why is there no subway graffiti any more?

    "It started with someone just writing their name — someone saw that, and added on to it," recalls New York graffiti artist Nicer, born Hector Nazario. "Letters going in front of letters, coming back through a letter, behind a letter, going across a letter... the subways became our playground," adds Riff170.

    New York in 1974 was a city in crisis. The Mayor, Abe Beame, slashed the city's budget in a bid to stave off bankruptcy(破产), which meant laying off school teachers, police officers and subway staff.

    "They were taking the money from the schools, there was a lot of corruption here, in this community, and so they took the after-school programmes away, and there was no outlets for this. So the outlet became our city," says Bronx-born designer Eric Orr.

    "It was like an explosion. The graffiti explosion. All of a sudden it took over the whole city. I don't know what happened, but overnight in the early 70s it was from no graffiti to all graffiti," says another former artist, Flint Gennari.

    Eric Felisbret, author and former graffiti artist, says graffiti culture was in a way a product of the civil rights movement. "It was never political," he says, "but many people were brought up with that, and to express yourself by breaking the law became a natural process for them."

    The graffiti pioneers came from all races, however. "There were writers that were African American, Latino - Puerto Rico, Dominican, Cuban - Jewish, Asian, and it became one unit — one family," says another graffiti pioneer, Roberto Gualtieri.

    Prof Gregory Snyder, sociologist and author of Graffiti Lives, says: "For lots of people, graffiti is ugly, vandalistic, and I'm not denying that. It's vandalism... now, oftentimes it's very clever vandalism. It can be written on a dumpster, like a garbage bin, and if someone's attempting to make a garbage bin look a little prettier maybe that's not the worst thing in the world." Although Mailer was not alone in welcoming the flowering of creativity, the authorities hated it, as did many passengers.

    So when Mayor Ed Koch took office, he was determined to clean up the city and set about targeting graffiti.

    "I remember in 1982 he brought everyone out to a train yard and there was a single train painted white," says former New York Daily News reporter Salvatore Arena. Trains were taken out of service and cleaned as soon as graffiti was spotted. Carriages were protected at night and the city agreed to ban the sale of spray cans.

    If in 1984 80% of subway carriages contained graffiti by May 1989 the network was graffiti-free. “Graffiti has gone through an evolution, and it will continue to evolve. It's now socially accepted in places where 20-30 years ago that would have been impossible. It's now showcased(展示) in certain museums —and let's say in another 30 years from now it may be hanging in the White House,” says Nicer.

    Nowadays painted graffiti is largely gone from the New York subway trains themselves and is seen instead on the walls and tunnels of the city. It has been replaced by scratchiti(刮擦艺术) created onto carriage windows using keys, knives. Unlike the vivid images of 40 years ago, these ghostly patterns are somehow easy to ignore. After all, graffiti has faded quietly into the background.

    Motherhood may make women smarter and may help prevent dementia (痴呆) in old age by bathing the brain in protective hormones (荷尔蒙) , U.S. researchers reported on Thursday.

    Tests on rats show that those who raise two or more litters of pups do considerably better in tests of memory and skills than rats who have no offsprings, and their brains show changes that suggest they may be protected against diseases such as Alzheimer's (早老痴呆症). University of Richmond psychology professor Craig Kinsley believes his findings will translate into humans.

“Our research shows that the hormones of pregnancy are protecting the brain, including estrogen(雌激素), which we know has many neuroprotective (保护神经的) effects,” Kinsley said.

    “It's rat data but humans are mammals just like these animals are mammals,” he added in a telephone interview. “They go through pregnancy and hormonal changes.”

    Kinsley said he hoped public health officials and researchers will look to see if having had children protects a woman from Alzheimer's and other forms of age-related brain decline.

    “When people think about pregnancy, they think about what happens to babies and the mother from the neck down,” said Kinsley, who presented his findings to the annual meeting of the Society of Neuroscience in Orlando, Florida.

    “They do not realize that hormones are washing on the brain. If you look at female animals who have never gone through pregnancy, they act differently toward young. But if she goes through pregnancy, she will sacrifice her life for her infant—that is a great change in her behavior that showed in genetic alterations to the brain.”

    Located in the checkroom in Union Station as I am, I see everybody that comes up the stairs.

Harry came in a little over three years ago and waited for the passengers from the 9:05 train.

    I remember seeing Harry that first evening. He wasn't much more than a thin, anxious kid then and I knew he was meeting his girl and that they would be married twenty minutes after she arrived. The passengers came up and I had to get busy. I didn't look toward the stairs again until it was nearly time for the 9:18 train and I was very surprised to see that the young fellow was still there.

    She didn't come on the 9:18 either, nor on the 9:40, and when the passengers from the 10:02 had all arrived and left, Harry was looking pretty desperate. He showed me the telegram he'd received: ARRIVE THURSDAY. MEET ME STATION. LOVE YOU. MAY.

    Harry met every train for the next three or four days, but in vain.

    Then came yesterday. I heard a cry and found that it was from Harry. He grabbed a girl who was small and dark. For a while they just hung there to each other laughing and crying and saying things without meaning. She'd say a few words like, "It was the bus station I meant" and he'd kiss her speechless and tell her the many things he had done to find her. What apparently had happened three years before was that May had come by bus, not by train, and in her telegram she meant "bus station," not "railroad station." She had waited at the bus station for days and had spent all her money trying to find Harry. Finally she got a job typing.

    "What?" said Harry. "Have you been working in town? All the time?"

    She nodded.

    "Didn't you ever come down here to the station?" He pointed across to a magazine stand. "I've been there all the time. I own it. I've watched everybody that came up the stairs."

    She began to look a little pale. Pretty soon she looked over at the stairs and said in a weak voice, "I never came up the stairs before. Harry, for three years, for three solid years, I've been right over there working right in this very station, typing, in the office of the stationmaster."

    As for old people, some of the applications are hard to use because they didn't grow up with them. They don't have simple models of how they should work, what to do when something doesn't work or where to go for help. We make it as easy as possible to be used for people who are not familiar with the technology.

    I think there is huge potential (潜力) and we are designing it. The ability to connect to friends, who remember the same movies and news and music, is really important, especially as people get old. They end up in retirement homes and they aren't always close to their friends. Allowing the network to help them connect with friends and family is a really powerful thing.

    My mother is an enthusiastic user of the Internet, although it took me years to get her to use e-mail. She was born with normal hearing, but lost it when she was 3. She was totally deaf for many years, until age 53, when she got ear aids. They work really well. That is a big change for her. But before then, her friends couldn't call her on the phone, so they insisted she use e-mail to communicate with them.

    Young people don't even think of the Internet as technology. It's just there, and they use it. There's been a very interesting change in communications styles between old people and young people. There are some kids who are now in their teens and aren't willing to make phone calls. And they think of e-mail as old-fashioned and slow.

    The reason why teens don't make phone calls seems to be that they don't know what to say. When they call they often stop for a while and there's this silence. On the other hand, texting is considered proper, and it's okay if you don't answer. You might have been distracted. It's not considered rude. But it is considered strange if you're in this kind of voice conversation and simply stop talking.

It was the early 1950s, and I was a member of the A class at Armidale Senior High School in norther New South Wales. 

In the second and third years we all did General Maths, and our teacher was Mrs Lindsay-Clare Lindsay. Her arrival at our classroom was always quick, "Good morning everyone!" Then our books would be out, and we would watch her closely. 

I've thought a lot about Clare Lindsay over the years. What was her special magic? There are two reasons and I think they're necessary for all excellent teachers. She loved her subject, and she loved us, in a patient and objective way. She had no favorites that I can remember, and she called us all by our first names pleasantly She had a way of teaching that I loved. 

"Now we could go down this path couldn't we? We could argue this, and then this, but that doesn't work because of this. No Can Do(NCD)!" She would put a big cross, and write" NCD" against what she had put down. "Right! Why not go down this new path?" And she would show us that this new way worked. It was fun. We, whether the poor students or the skilled, all did well because of her. I've never found maths difficult, and I_put_that_skill_down_to_her. 

In the fourth and fifth years,we were divided into the science and arts streams(按学生能力划分的班级), and Mrs Lindsay didn't teach us any more. But as the Leaving Certificate exams were coming, one of my friends became nervous about how much maths he didn't know. With great courage, he went to see Mrs Lindsay, and asked if she would help him prepare for his General Maths paper. "Of course!" she said, and did just that, after school, in her own time. He passed. What a good teacher!