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　　After lots of hype, the new iPhone 3GS has arrived, boasting an improved camera, better battery life, and speedier performance．But is it a must?

　　The iPhone 3GS is available in two versions: 16GB and 32GB．The 16GB version costs ＄199, while the 32GB version costs ＄299．From the outside, the iPhone 3GS looks exactly like the iPhone 3G．Like the iPhone 3G, the new model comes in black and white versions, and sports a 3.5－inch touch screen．Most of the changes to the iPhone 3GS have been made on the inside．Apple says that battery life is better, but the biggest boost is in the iPhone's speed: The iPhone 3GS runs twice as fast as the iPhone 3G．Instead of a lot of software installed on it, the iPhone 3GS comes with the most recent version of the iPhone Software－version 3.0－installed, but it does come with easy access to Apple's App Store．The speedier performance of the iPhone 3GS extends to surfing the Web, too．You can see entire Web pages, and can zoom(急速移动)in and out with ease．

　　The notable new messaging feature on the iPhone 3GS is support for MMS．You can send pictures and videos by SMS, rather than having to send them via e－mail．Other new and very－handy e－mail features include the ability to search through your e－mail messages and contacts, as well as the option to use a landscape－oriented keyboard when composing messages．

　　The camera has been upgraded from 2 megapixels(兆像素)to 3 megapxiels, and adds auto－focus．If you already own an iPhone 3G, the iPhone 3GS may not be worth the additional cost, since you can get many of its cool features for free with the iPhone 3.0 software upgrade．But if you've been using an older iPhone or smart phone, or are new to the smart phone world, the iPhone 3GS will amaze you with its speed and plentiful features．

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　　Xiangzi－Lucky, in English－is appropriately named．His owner Qiu Hong, a sports marketer, lets the dog enjoy two daily walks, a collection of imported American toys, ＄300 worth of monthly food and treats and his own sofa in her high－rise apartment．When Ms．Qiu feels bored, she takes Xiangzi out for a long run in her car．

　　In a sense, Xiangzi is not just a dog, but a social phenomenon－and, perhaps, a marker of how quickly the Chinese nation is booming through its transformation from poor farmer to first－world citizen．Twenty years ago, there were hardly any dogs in Beijing, but now there’re 900, 000 registered dogs with countless thousands of others unlicensed．How this came to be is, in some ways, the story of modern China as well．

　　“People used to be focused on improving their own lives, and they weren't really acquainted with raising dogs,” said Ms．Qiu．“But with the improvement in the economy, people's outlooks(观念)have changed．”

　　Having a dog can be a way to relieve the stress in people's lives, but mostly Beijing dogs have, as in the West, become objects of affection－even devotion－by their owners．It's easy to find dog－treat stores, dog Web sites, dog social networks, dog swimming pools－even, for a time recently, a bring－your－dog cinema and a bring－your－dog bar on Beijing's downtown nightclub row．

　　The doglike devotion of pet owners here seems to have softened the city government heart．In 1994, Beijing officials relaxed their no－dog policy to“severely restrict” dogs．In 2003, it was changed again to allow anyone to own a dog, but to limit city dogs to no more than 35 centimeters in height．And nowadays the restriction seems to be loosely carried out．

　　As for stir－fried Pekingese(京叭狗)－well, that dog, too, may have seen its day．A formal suggestion to ban the eating of dogs has been made by a law professor named Chang Jiwen, who considered himself“not so much a dog lover as a China lover”．“With China developing so quickly, more people should know how to treat animals properly,” he said in a telephone interview．

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　　The year is 2094．It has been announced that a comet(彗星)is heading towards the Earth．Most of it will miss our planet, but two pieces will probably hit the southern half of the Earth．

　　On 17 July, a piece four kilometers wide enters the Earth's atmosphere with a massive explosion．About half of the piece is destroyed, but the remaining part hits the South Atlantic at 200 times the speed of sound．The sea boils and a huge hole is made in the sea bed．Huge waves are created and spread outwards from the hole．The wall of water, a kilometer high, rushes towards southern Africa at 800 kilometers an hour．Cities on the African coast are totally destroyed and millions of people are drowned．

　　Before the waves reach South America, the second piece of the comet lands in Argentina．Earthquakes and volcanoes are set off in the Andes Mountains．The shock waves move north into California and all around the Pacific Ocean．The cities of Los Angeles, San Francisco and Tokyo are completely destroyed by earthquakes．Millions of people in the southern half of the earth are already dead, but the north won't escape for long．Because of the explosions, the sun is hidden by clouds of dust, and temperatures around the world fall to almost zero．Crops are ruined．The sun won't be seen again for many years．Wars break out as countries fight for food．A year later, no more than 10 million remain alive．

　　Could it really happen? In fact, it has already happened more than once in the history of the Earth．The dinosaurs were on the Earth for over 160 million years．Then 65 million years ago they suddenly disappeared．Many scientists believe that the Earth was hit by a piece of object in space．The dinosaurs couldn't live through the cold climate that followed and they died out．Will we meet the same end?

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　　Exercise may hold the key to youth, according to a study published recently which showed people who keep fit are up to nine years biologically younger than those who do not．

　　The findings are the first to show in humans how keeping fit affects the ageing process．

　　The study of 2, 401 twins found that a sedentary(惯于久坐的)lifestyle raises the risk of a range of problems from heart disease to cancer and appears to play a key role in the ageing process．

　　It all appears to boil down to the length of structures called telomeres－which protect the DNA on the chromosomes(染色体), the researchers from King's College London wrote in the Archives of Internal Medicine．

　　Many studies have shown telomeres get shorter over time, suggesting the cells are ageing or dying．The study, which extracted a DNA sample from their volunteers, found people who exercised more each week had longer telomeres．

　　Exercise lowers the risk of a range of problems such as heart disease, diabetes(糖尿病)and cancer, the researchers said．

　　“It is not just walking around the block．It is really working up a sweat,” said Tim Spector, a genetic epidemiologist(流行病学家)who led the study, in a telephone interview．

　　The study found people who exercised vigorously 3 hours each week had longer telomeres and they were 9 years biologically younger than people who did under 15 minutes．

　　Spector's team, who also adjusted for body weight, smoking, economic status and physical activity at work, also said moderate exercise for 1－1/2 hours each week provided a four－year advantage．

　　The reason why exercise has this effect is not clear but we believe physical activity somehow defends against the natural process．