阅读下列材料，从每题所给的四个选项（A、B、C和D）中，选出最佳选项.

Five years ago, David Smith wore an expensive suit to work every day. "I was a clothes addict(有瘾的人)," he jokes. "I used to carry a fresh suit to work with me, so I could change if my clothes got wrinkled(有褶皱的)." Today David wears casual clothes (便装) to the office. He hardly ever wears a necktie. "I am working harder than ever." David says, "and I need to feel comfortable."

More and more companies are allowing their office workers to wear casual clothes to work. In the United States, the change from formal to casual office wear has been gradual. In the early 1990s, many companies allowed their employees to wear casual clothes on Friday. This became known as "casual Friday". "What started out as an extra one-day-a-week benefit for employees has really become an everyday thing." said business consultant Maisly Jones.

Why have so many companies started allowing their employees to wear casual clothes? "One reason is that it's easier for a company to attract new employees if it has a casual dress code." "A lot of young people don't want to dress up for work," says Owen Black, the owner of a software company, "so it's hard to hire people if you have a conservative (保守的) dress code." Another reason is that people seem happier and more productive when they are wearing comfortable clothes. In a study conducted by Levi Company, 85 percent of employers said that they believe that casual dress improves employee morale (心境, 士气). Only 4 percent of employers said that casual dress has a negative influence on productivity. Supporters of casual office wear also argue that a casual dress code helps them save money. "Suits are expensive, if you have to wear one every day," one person said. "For the same amount of money, you can buy a lot more casual clothes."

    Birthdays often involve surprises.But this year's surprise on the birthday of the great British playwright William Shakespeare is surely one of the most dramatic.

    On April 22,one day before his 441st birthday anniversary,experts discovered that one of the most recognizable portraits（画像）of William Shakespeare is a fake.This means that we no longer have a good idea of what Shakespeare looked like."It's very possible that many pictures of Shakespeare might be unreliable because many of them are copies of this one,"said an expert from Britain's National Portrait Gallery.

    The discovery comes after four months of testing using modern chemistry technology.The experts from the gallery say the image—commonly known as the "Flower portrait"—was actually painted in the 1800s,about two centuries after Shakespeare's death.The art experts who work at the gallery say they also used modern chemistry technology to check the paint on the picture.These checks found traces of paint dating from about 1814.Shakespeare died in 1616,and the date that appears on the portrait is 1609.

    “We now think the portrait dates back to around 1818 to 1840.This was when there was a renewed interest in Shakespeare's plays,”Tarnya Cooper,the gallery's curator（馆长）,told the Associated President.

    The fake picture has often been used as a cover for collections of his plays.It is called the Flower portrait because one of its owners,Desmond Flower,gave it to the Royal Shakespeare Company.

    “There have always been questions about the painting,”said David Howells,curator for the Royal Shakespeare Company.“Now we know the truth,we can put the image in its proper place in the history of Shakespearean portraiture.”

    Two other images of Shakespeare,are also being studied as part of the investigation and the results will come out later this month.

    Researchers are trying to figure out exactly when and where a lizard got trapped in the sap(汁、液) of a tree. Over time, the tree sap turned into amber (琥珀), preserving the lizard's mains, which a man discovered and donated to the Miller Museum of geology at Queen's University. But the man didn't report the amber's age and where he got it.

    “The man who donated it died, unfortunately,” said Ellen Handyside, an undergraduate student at Queen's University. “We are really starting from scratch in determining its history Ellen Handyside is leading the research into the amber-surrounded lizard. She and her colleagues analyzed the chemical composition of the 4.7-inch -long piece of amber and learned some facts. “The amber wasn't actually artificial,” she told Live Science, “and we found that it did match up quite well to an amber sample.”

    The researchers analyzed the amber's carbon and hydrogen isotopes(同位素) and the results indicated that the amber was formed from the sap of a flowering tree. Moreover, the results suggested that the tree and the lizard, for that matter, lived in an area with a lot of rainfall and dated to the Neogene, a period that lasted from the end of the Paleogene Period 23.03 million years ago to the beginning of the present Quatemary Period. Next, the scientific team realized that the 2.7-inch-long lizard was likely a gecko(壁虎), according to a detailed, 3D, digital model of the animal's body that the researchers created through X-ray microscopy scans.

“We looked at the skull —the teeth are in place and the ear bones are there too. And we've even got some flesh, skin and its long toes,” Handyside said. “It's fantastic!” She said she hoped that they could figure out how the creature fit into the gecko family tree. “When you think of a gecko, you think of short and fat toes and sticky pads. That isn't what we're looking at, but it's more likely to live in trees. If it were a tree-living creature, then its death actually could make more sense,” Handyside said.

Welcome to your future life!

    You get up in the morning and look into the mirror. Your face is firm and young­looking. In 2035, medical technology is better than ever. Many people at your age could live to 150, so at 40, you're not old at all. And your parents just had an anti­aging (抗衰老的) treatment. Now, all three of you look the same age!

    You say to your shirt, "Turn red." It changes from blue to red. In 2035, "smart clothes" contain particles (粒子) much smaller than the cells in your body. The particles can be programmed to change your clothes' color or pattern.

    You walk into the kitchen. You pick up the milk, but a voice says, "You shouldn't drink that!" Your fridge has read the chip (芯片) that contains information about the milk, and it knows the milk is old. In 2035, every article of food in the grocery store has such a chip.

    It's time to go to work. In 2035, cars drive themselves. Just tell your "smart car" where to go. On the way, you can call a friend using your jacket sleeve (袖子). Such "smart technology" is all around you.

    So will all these things come true? "For new technology to succeed," says scientist Andrew Zolli, "It has to be so much better that it replaces what we have already." The Internet is one example-what will be the next?

    With more and more people swimming at beaches every year, the problem of sharks (鲨鱼) takes on new importance. There are people who still insist that sharks never attack human beings unless they are bleeding or wounded, but this belief has not been clearly proved. In the past few years, on both the Atlantic and Pacific coasts, there have been cases of shark attacks which resulted in death. And just how many of the swimmers who have disappeared were victims of shark attacks will never be known. Clearly, these violent fish can be dangerous. Several species are known to attack human beings, and it is believed by some experts that certain sharks, once having tasted human blood, develop a taste for it.

    The chances that one will come across a shark are small, but certain precautions should be taken by everyone. (A precaution is something you do in order to prevent something dangerous or unpleasant from happening.) Putting hands or legs over the side of a boat in warm waters is to be avoided. Swimming far out from beaches is inviting trouble. No swimmer should go great distances from shore alone, or go into the water when nobody else is about. Skin divers, particularly those who go deep down in the water or among rocks and ledges (暗礁) that serve as hiding places for sharks, are taking unnecessary risks.

    If one is in a boat that is rubbed against by a shark, he should remember the creature is not trying to upset his boat; it is probably trying to rub off sea lice (海虱). A blow, especially on the nose, will drive it off. If a swimmer comes across a shark, he should swim away as quietly as possible, trying to avoid making it angry. He should also head for shore (岸) as quickly as possible.