Can people change their skin color without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin color.
The gene comes in two versions, one of which is found in 99 per cent of Europeans. The other is found in 93 to 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.
Scientists have changed the color of a dark-striped zebrafish（斑马鱼） to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebrafish skin color is determined by pigment cells, which contain melanin (黑色素). The number, size and darkness of melanin per pigment cell determine skin color.
It appears that, like the golden zebrafish, light-skinned Europeans also have a mutation (变异) in the gene for melanin production. This results in less pigmented skin.
However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebrafish genes.
Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun (太阳光紫外线), which can cause skin cancer.
But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.
Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin color, said Cheng.
The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin color without damaging it like chemical treatment did on Michael Jackson.
【小题1】 The passage mainly tells us that ________.

Visitors worry that London is an expensive city but there really are so many things to do for




free in London from museums and galleries to free music and walking tours.
Art Galleries
Tate Modern and Tate Britain are exceptional national art galleries housing some of the finest artworks in the world. Tate Modern focuses on contemporary art while Tate Britain displays British Art from the sixteenth century to the present day.
Museums
All of London's major museums are free, but most offer some special exhibitions for a fee. My favorite is the Museum of London where you can learn the history of London from Roman times to today. Other great major museums are the British Museum, the V&A, the Science Museum, and the      Natural History Museum. Oh, and I love the Geffrye Museum. And the. Now I can't decide which is the best!
Many of London's major art galleries and museums are open in the evening and often have special evening events. This can be a great way to relax at the end of a busy day seeing the sights. The main London galleries and museums are air-conditioned so it can be a wonderful way to cool down in the height of summer in the city. Galleries and museums are not open late every night so here is a handy list to help you plan your days and evenings.
Royal Parks
Many people say the Queen Mary's Rose Gardens in Regent's Park is their favorite spot in London, and who am I to argue? I would also recommend St. James's Park as it offers one of the best views of Buckingham Palace. Hyde Park is enormous and includes the ever popular Diana Memorial Fountain and the Peter Pan Statue.
There are often free talks and guided walks in the royal parks so do check the What's On section of the Royal Parks website.
Changing of the Guard
No visit to London is complete without seeing this military tradition. The Queen's Guard in London changes in the Forecourt inside the gates of Buckingham Palace at 11:30am every day in the summer and every other day in the winter. Get there early and view the spectacle from outside the front gates.
53. The passage is intended to _________.
A. recommend some free scenic spots to tourists       
B. help visitors save money while visiting Ireland
C. advise travelers how to choose art articles      D. tell readers London’s wonderful history
54. If you visit some museums in London in the evening, you ________.
A. can see all the artworks free of charge               B. have to endure the heat of the summer
C. need to pay admission for general exhibition  
D. may have a chance to enjoy some special events
55. In order to watch Changing of the Guard in summer, visitors have to _________.
A. gain access to the front gates after 11:30 a.m.
B. pay a sum of money to enter the Royal Parks
C. arrive at Buckingham Palace before 11:30 a.m.
D. come through the gates of Buchingham Palace

From now on, never spend your precious time thinking of reasons for your failures and shortcomings. Instead, realize that the seeds of success were planted within you when you were born. Only you have the power to make those seeds grow.
The seeds, and the power to grow them, are contained in the most awesome machine ever created：the human mind. Success is a choice and not a chance. You were born a winner. You were born rich. You can be a success if only you make the right choice.
You cannot be successful without first developing your self-esteem. Your level of self-esteem is always based on the degree of control that you are able to exercise over yourself, and thus over your life. People with low self-esteem are people who do not believe that they have any power, or responsibility for their lives. They are the perennial(长期的) victims and martyrs. They are leaves tossed(摇摆) by the winds of chance blown about with any sudden change in the weather.
You can exercise control over your life only to the degree that you believe that you are responsible for everything that happens in your life. Failures think that everything happens by accident and chance. Successful people realize that they are responsible.
Everything happens as a result of something. If we can identify the cause, we can control the effect. We are responsible for what we choose to think and believe. One generally rises to the level that one expects. We are responsible for setting our expectations. Our success is dependent upon our level of confidence.
If you associate with positive-thinking people, you are definitely going to achieve success. On the contrary, the opposite happens. We are responsible for finding, planting, and nurturing the seeds that contain future victory, born from setbacks.
In short, in all areas of your life, whether they be financial, physical, emotional, or spiritual, you are responsible. Once you recognize this, accept it, and firmly believe it, you are on the road to success.
【小题1】People with low self-esteem are compared to leaves because they ______________  .

A．Success is a choice.	B．The secrets of success.
C．Develop our confidence.	D．How to achieve success.

When you’re surfing the Internet on your laptop from your dorm or home, do you know your personal details are being gathered secretly? And would you be surprised to know the information may be sold cheaply to advertisers and marketers?
According to an investigation by The Wall Street Journal, all it takes is a tiny file in a computer-a single code consisting of a long series of numbers and letters- to record the computer user’s age, gender, location, favorite movies and hobbies.
The newspaper reports that Lotame Solutions Inc., a New York company, uses sophisticated(高科技) software called a "beacon" to capture what people are typing on a website.
Lotame packages that data into profiles（个人资料）about individuals, only without their names, and sells the profiles to companies seeking customers．Batches of such data may be sold for a few dollars.
The Wall Street Journal survey discovered that spying on Internet users is one of the fastest-growing businesses on the World Wide Web.
The "cookie"- a tiny text file put on your PC by websites or marketing firms which might be used to remember your preferences for one site, or to track you across many sites is already old news．There are new and more complex tools such as "beacons" which scan in real time what people are doing on a webpage．These beacons instantly assess the Internet user’s location, income, shopping interests and even medical conditions.
Millions of Internet users around the world also face unprecedented（空前的）threats．Private, sensitive, personal and business information is being gathered and sold without their knowledge.
Companies insist the information they gather is anonymous and the data is used harmlessly. But the technology has grown so powerful that even some of the biggest websites in the US don’t know that they were installing intrusive files on visitors’ computers．These include MSN.com and Yahoo.com.
Next time you visit a webpage and find an ad banner advertising something you’ve been planning to buy, don’t be amazed that your computer can read your mind.
【小题1】The purpose of the passage is to          .

If you are afraid of the dark，it’s not a big deal．It’s perfectly normal to feel afraid After all，animals do too. “Fear matters，”says Karen Warkentin，an ecologist．“It’s a good thing，” she adds, “because fear makes you do things that keep you alive.”
Like kids，many animals experience fear and they respond to the feeling in variety of ways．A frightened turtle pulls its head and legs inside its shell．A  small fish will swim away when a big，hungry fish approaches．
Some animals respond to fear in ways you might not expect．The first example is that the fear of being eaten can scare some frogs right out of their eggs. Warkentin made the surprising discovery while studying red—eyed tree frogs in Costa Rica.
In this species，female frogs attach jellylike clumps（果冻一样的块状物）of their eggs to the undersides of leaves．The leaves hang on branches that dangle（悬挂）over ponds．After they hatch from the eggs，the tadpoles（蝌蚪）then fall into the water，where they eventually grow into adult frogs.
Tree frog eggs usually grow for 6 days before hatching．If they sense that a hungry snake is about to attack，however，they can hatch up to 2 days ahead of schedule. As the snakes are unable to swim，by falling into the water early，the tadpoles can escape.
If hatching early helps protect red—eyed tree frogs from snakes，you might wonder why their eggs don’t always hatch sooner．It turns out that hatching early brings its own danger．Once tadpoles land in the water，hungry fish and other animals like to eat them too．Staying in their eggs for a full 6 days，then，allows frog embryos（胚胎）to grow big and strong．This extra growth improves their chances of surviving in the water．
【小题1】It can be inferred from the passage that fears      .