Black History Month is also known as the African-American History Month. It is celebrated all over the United States of America and Canada in the month of February, while in the United Kingdom it is celebrated in October. Each and every school and university conducts various activities to make the generation aware of the importance that African-American history holds in the nation. The electronic media is filled with themes inrelevance to the occasion, and many activities are carried out across the country to remember the contribution made by African-American citizens in the development of this nation.

    Black History Month was first started bya famous African-American historian Dr. Carter G. Woodson in the year 1926. February was chosen as the month to celebrate the African-American history because it was the birth month of two of the most highly valued people among African-Americans. These were President Abraham Lincoln, who freed the slaves, and Frederick Douglass, who was also the first vice presidential nominee (被任命者) amongAfrican-Americans. Initially, Black History Month was known as the “NegroHistory Week”. This was Dr. Woodson's attempt to encourage awareness amongcitizens about the contribution of African-Americans towards the building of the nation. It was only in the early 1970's that the name “Negro History Week”changed to “Black History Month”. And later, in the year 1976, the entire monthof February was declared to be the National African-American History Month, orthe Black History Month.

Every year, National African-AmericanHistory Month is celebrated by many activities with various ideas and themesfor the younger generation. In 2013, Black History Month celebrates the 50^th anniversary of the March on Washington at which Martin Luther King, Jr. gavehis famous speech “I have a dream”. It also marks the 150^th anniversary of the Emancipation Proclamation (解放黑奴宣言). The theme for Black History Month in 2014 is “Civil Rights in America” remembering the important milestones by African-Americans and others in the battle for civil rights and equaltreatment under the law.

    Facebook is an Internet-based social network site that lets people get in touch with family and friends and reach out to people with common interests around the world, all through computer. It is very popular, with more than 900 million users. If Facebook were a country, it would have about three times the population of the United States.

    Documents filed with US. financial regulators say Facebook has hundreds of millions of active users who send billions of messages each day and upload 250 million photographs on their personal pages. Facebook users have registered 100 billion “friends.”

    On Facebook, “Friending” someone means you add the person to your list of people you can communicate with directly, which often allows the person to see more information about you than you share with the general public.

    Facebook was started by Mark Zuckerberg and other students at Harvard University in 2004, and has grown at an amazingly fast pace.

    Facebook makes money when advertisers pay to get access to hundreds of millions of Facebook users. Advertisers can often direct their messages to the people most interested in their products because Facebook computers keep track of information that users place on their pages. For example, a person interested in diving, planning a wedding, looking for work, or suffering from diabetes(糖尿病) may see advertisements related to those topics.

    Facebook has become so much a part of the culture of the United States and other nations that it has been the subject of a Hollywood movie. It is a key marketing tool for many businesses, and its users' content has been used as evidence in some divorce or criminal cases.

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    Car Hire

    Hiring a self-drive car really adds to the enjoyment of your holiday.There are so many places of interest to visit,and if you enjoy seeing more than just the city center there's no better way to explore than by car.

    Hire Charges:

    What's included

a) Unlimited mileage （英里数）.

b) Expenses on oil,maintenance and repairs,which will be repaid on production of invoices.

C) Full insurance except personal accident (see below).

What's not included

a) Personal accident insurance.

b) Garaging,petrol,parking and traffic fines.

    Conditions of Hire:

    The shortest rental period at these special low prices is three days.For prices for periods of one or two days you only see our representative at the hotel.

    Car hire must be booked six weeks or more before arrival in London to guarantee a car.But if you have been unable to make a booking in advance please see our representative at the hotel who may still be able to help you.

    The car types on the sheet are examples of the types of cars in each price range,but particular car cannot be guaranteed.

    Upon delivery the driver (s) will be asked to sigh the car hire company's Condition of Hire.

    If you decide to hire a car,just fill in the Booking Form and return it to us.A booking fee of £ 12 as part of the car hire cost is required.

    Should you be forced to cancel your car hire booking after payment in full (two weeks before date of hire),a cancellation charge of £ 12 will be made.

    The Nazca Lines are a series of large ancient geoglyphs (地画) in the Nazca Desert, in southern Peru. It is ranging from geometric patterns to drawings of different animals and stylized human-like forms. The ancient lines can only be truly taken in from high in the air, leaving generations puzzled as to how these precise works could have been completed long before the documented invention of human flight.

    The Lines were first spotted when commercial airlines began flying across the Peruvian desert in the 1920,s. Who built them and what was their purpose? Are they roads, star pointers，maybe even a gigantic map? If the people who lived here 2,000 years ago had only a simple technology, how did they manage to construct such precise figures? Did they have a plan? These markings are like a vast puzzle.

    The Nazca Lines are the most outstanding group of geoglyphs in the world. There are also huge geoglyphs in Egypt, Malta，United States (Mississippi and California), Chile，Holivia and in other countries. But the Nazca geoglyphs, because of their numbers， characteristics, dimensions and cultural continuity as they were made and remade throughout a certain history period, form the most impressive archeological (考古学的) group.

    The Nazca plain is unique for its ability to preserve the markings upon it, due to the combination of the climate (one of the driest on Earth, with only twenty minutes of rainfall per year) and the flat, stony ground which minimizes the effect of the wind at ground level. With no dust or sand to cover the plain and little rain or wind to erode (腐蚀) it, lines drawn here tend to stay drawn. These factors, combined with the existence of lighter-colored subsoil beneath the desert surface, provide a vast writing pad that is suited to the artist who wants to leave his mark eternal.

    Following news of the potential for life on the recently-discovered TRAPPIST-1 system, there may be another competitor ready to take its place.

    With the help of the Cassini spacecraft, NASA (National Aeronautics and Space Administration) scientists have picked up the first evidence that chemical reactions are taking place deep below the surface of Enceladus, Saturn's (土星的) sixth-largest moon. This means that there could be life in Enceladus' warm underground seas.

    An early study found that liquid oceans exist miles below Enceladus' surface. But to reveal what is happening down there, scientists must rely on the plumes (股) of water that spray (喷射) through cracks in Enceladus' icy surface. In October 2015, NASA sent Cassini into a deep dive into one of the plumes.

    Cassini's findings, published on April 13 in the journal Science, showed that hydrogen (氢) not only exists on Enceladus, but is also responsible for a chemical reaction between hot rocks and water in the ocean beneath its surface.

    This same process on Earth provides energy for entire ecosystems around volcanic vents (火山口). There, tiny creatures are able to survive without sunlight, using hydrogen and carbon dioxide as fuel in a process known as “methanogenesis (甲烷生成)”.

    The discovery of this chemical energy source on Enceladus means it could be a very good candidate to host life.

    “Confirmation (确认) that the chemical energy for life exists within the ocean of a small moon of Saturn is an important milestone (里程碑) in our search for habitable (可居住的) worlds beyond Earth,” Linda Spilker, Cassini project scientist at NASA, told the Daily Mail.

    Alien life was once only thought possible on habitable planets within the “Goldilocks zone” – far enough from our sun not to be a fireball, but not so far as to be freezing.

    Research on Enceladus is still in its early stages, but the recent findings have important meanings for future exploration.

    “At present, we know of only one genesis (诞生) of life, the one that led to us,” David Rothery, professor of planetary geosciences (行星与地球科学) from the Open University in the UK, told The Telegraph.

    “If we knew that life had started independently in two places in our solar system, then we could be pretty confident that life also got started on some of the tens of billions of planets and moons around other stars in our galaxy,” he said.

Biologists from the John Innes Centre in England discovered that plants have a biological process which divides their amount of stored energy by the length of the night. This solves the problem of how to portion out (分配) energy reserves during the night so that the plant can keep growing, yet not risk burning off all its stored energy.

While the sun shines, plants perform photosynthesis (光合作用). In this process, the plants change sunlight, water and carbon dioxide into stored energy in the form of long chains of sugar, called starch (淀粉). At night, the plants burn this stored starch to fuel continued growth.

"The calculations are precise so that plants prevent starvation but also make the most efficient use of their food," said study co-author Alison Smith. "If the starch store is used too fast, plants will starve and stop growing during the night. If the store is used too slowly, some of it will be wasted. "

The scientists studied the plant Arabidopsis, which is regarded as a model plant for experiments. To give the plants some math tests, the biologists let night arrive unexpectedly early or late for them.

During one of the exams, they shut off the lights early on them that had been grown with twelve-hour days and nights. Putting them into darkness after only an eight-hour day means they didn't have time to store as much starch as usual. And this forced the plants to adjust their normal nightly rhythm.

Amazingly, even after this day length trick, the plants did very well in their exams and ended up with just five percent of starch left over at the end of the night. They had neither starved, nor stored starch that could have been used to fuel more growth.

The authors suggested that similar biological calculators may explain how a migratory bird, the little stint, can make a five-thousand-kilometer journey to their summer habitat in the Arctic and arrive with enough fat reserves to survive only approximately half a day more, on average.

The results of the study were published in e Life.