Languages have been coming and going for thousands of years, but in recent times there has been less coming and a lot more going. When the world was still populated by hunter-gatherers, small, tightly knit (联系)groups developed their own patterns of speech independent of each other.Some language experts believe that 10,000 years ago, when the world had just five to ten million people, they spoke perhaps 12,000 languages between them.

Soon afterwards, many of those people started settling down to become farmers, and their languages too became more settled and fewer in number. In recent centuries, trade, industrialization, the development of the nation-state and the spread of universal compulsory education, especially globalisation and better communications in the past few decades, all have caused many languages to disappear, and dominant languages such as English, Spanish and Chinese are increasingly taking over.zxxk

At present, the world has about 6,800 languages. The distribution of these languages is hugely uneven. The general rule is that mild zones have relatively few languages, often spoken by many people, while hot, wet zones have lots, often spoken by small numbers. Europe has only around 200 languages; the Americas about 1,000; Africa 2 400; and Asia and the Pacific perhaps 3,200, of which Papua New Guinea alone accounts for well over 800. The median number (中位数)of speakers is a mere 6,000, which means that half the world’s languages are spoken by fewer people than that.

Already well over 400 of the total of, 6,800 languages are close to extinction(消亡), with only a few elderly speakers left. Pick, at random, Busuu in Cameroon (eight remaining speakers),Chiapaneco in Mexico(150), Lipan Apache in the United States(two or three)or Wadjigu in Australia (one, with a question-mark): none of these seems to have much chance of survival.

  As cultural symbols go， the American car is quite young． The Model T Ford was built at the Piquette Plant in Michigan a century ago， with the first rolling off the assembly line （装配线）on September 27， 1908． Only eleven cars were produced the next month． But eventually Henry Ford would build fifteen million of them．

    Modern America was born on the road，behind a wheel． The car shaped some of the most lasting aspects of American culture： the roadside diner， the billboard， the motel，even the hamburger． For most of the last century， the car represented what it meant to be American﹣going forward at high speed to find new worlds． The road novel， the road movie， these are the most typical American ideas， born of abundant petrol， cheap cars and a never﹣ending interstate highway system， the largest public works project in history．

    In 1928 Herbert Hoover imagined an America with "a chicken in every pot and a car in every garage．" Since then， this society has moved onward， never looking back， as the car transformed America from a farm﹣based society into an industrial power．

    The cars that drove the American Dream have helped to create a global ecological disaster． In America the demand for oil has grown by 22 percent since 1990．

    The problems of excessive（过度的） energy consumption， climate change and population growth have been described in a book by the American writer Thomas L． Friedman． He fears the worst， but hopes for the best．

    Friedman points out that the green economy（经济）is a chance to keep American strength． "The ability to design， build and export green technologies for producing clean water， clean air and healthy and abundant food is going to be the curreney of power in the new century．"

Teens and younger children are reading a lot less for fun, according to a Common Sense Media report published Monday.

While the decline over the past decade is steep for teen readers, some data in the report shows that reading remains a big part of many children’s lives, and indicates how parents might help encourage more reading.

According to the report’s key findings, “the proportion (比例) who say they ‘hardly ever’ read for fun has gone from 8 percent of 13-year-olds and 9 percent of 17-year-olds in 1984 to 22 percent and 27 percent respectively today.”

The report data shows that pleasure reading levels for younger children, ages 2-8, remain largely the same. But the amount of time spent in reading each session has declined, from closer to an hour or more to closer to a half hour per session.

When it comes to technology and reading, the report does little to counsel (建议) parents looking for data about the effect of e-readers and tablets on reading. It does point out that many parents still limit electronic reading, mainly due to concerns about increased screen time.

The most hopeful data shared in the report shows clear evidence of parents serving as examples and important guides for their kids when it comes to reading. Data shows that kids and teens who do read frequently, compared to infrequent readers, have more books in the home, more books purchased for them, parents who read more often, and parents who set aside time for them to read.

As the end of school approaches, and school vacation reading lists loom (逼近) ahead, parents might take this chance to step in and make their own summer reading list and plan a family trip to the library or bookstore.