Did you know that the Chinese built the largest canal in the world? Its length of 1,104 miles easily compares with a route linking New York and Florida. Connecting five river systems and four provinces, it ends at Beijing in the North and Hangzhou in the south. For this reason, it is officially called the Beijing-Hangzhou Grand Canal.

In 486 B.C., the leader of the State of Wu, to transport goods to the northern areas of China, constructed a man-made channel using already existing waterways to link the Yangtze and Huai rivers. It was this channel that laid the foundation for the future longer Grand Canal. More than 1000 years later, Emperor Yang of Sui Dynasty had the old canals rebuilt and connected to form what we know today as the Grand Canal.

Then in 1403,Emperor Yongle of the Ming Dynasty transferred his capital from Nanjing to Beijing. In order to feed all those moving North, he had to transport grain from the south along the Grand Canal. To restore the Canal, more than 47,000 men were employed.

The canal soon became the economic lifeline of the empire. Grain was not the only trade goods transported North on the waterways. Salt was another, as well as wine and tea. Goods traded from the North included cotton, wool, coal, flour, precious stones, and dried meat. At times, more than 120,000 soldiers and officers were needed to operate the almost 12,000 ships that annually travelled the Grand Canal.

With the expansion of the railway system in the mid-1800s, the Grand Canal became less and less important to traders. Today, few goods are transported along its waterways. Still, the current South-North Water Transfer Project proves that the Chinese government still sees the Grand Canal important to the welfare of China. The aim of this costly project is to divert huge amounts of water every year from the Yangtze River to the drier regions in the north.

【推荐2】Farmers in southern Italy are planting avocados and mangos. Tropical creatures such as the rabbitfish are turning up in Mediterranean nets. And Bordeaux winemakers fear that their Merlot grapes may become extinct. Fifty years ago all this would have been unthinkable. But since the early 1980s rising temperatures have forced some farmers to change grapes for passion fruit. Italy and France have long been proud of their cuisines. Both countries jealously guard the rules that say only ham made in Parma can be called “ Prosciutto di Parma”, and only fizzy wine made in Champagne can be called “Champagne Roquefort”.

The fact of having been grown somewhere famous has traditionally been seen as a guarantee of quality. But climate change could upset that. Take polenta, a popular Italian dish consisting almost entirely of ground corn. High temperatures and drier weather have already reduced corn yields in southern Italy. If this pattern continues and spreads northwards, will Italian polenta-makers have to order their corns from elsewhere?

It is said that wheat yields will sharply fall there if the temperature keeps on rising. So should people worry about the future of spaghetti? Gabriele Cola, a researcher at Milan University, talks about the short term. “I don’t see crops at serious risk. Because farming is technologically capable, it can always respond to changes,” he says. Increased irrigation can counter the effects of drought. Scientists may also breed more resistant varieties of crops. But in the long run deeper change seems likely. If temperatures rise constantly, farmers in northern Europe may find they can grow southern staples; polenta may invade Germany. And southern locals may have to adapt. If tropical fruit continues to thrive in Sicily, could ham and pineapple pizza one day be considered authentically Italian?

【推荐3】The most intensive period of speech and language development for humans is during the first three years of life, a period when the brain is developing and maturing. These skills appear to develop best in a world that is rich with sounds, sights, and consistent（一致的，协调的，相容的）exposure（揭发）to the speech and language of others.

There is increasing evidence suggesting that there are “critical periods” for speech and language development in infants and young children. This means that the developing brain is best able to absorb a language, any language, during this period. The beginning signs of communication occur during the first few days of life when an infant learns that a cry will bring food, comfort, and companionship. As they grow, infants begin to sort out the speech sounds (phonemes) or building blocks that compose the words of their language. Research has shown that by six months of age, most children recognize the basic sounds of their native language.

As the speech mechanism (jaw, lips, and tongue) and voice mature, an infant is able to make controlled sound. By six months of age, an infant usually babbles or produces repetitive syllables such as “ba, ba, ba” or “da, da, da.” By the end of their first year, most children have mastered the ability to say a few simple words. Children are most likely unaware of the meaning of their first words, but soon learn the power of those words as others respond to them.

By eighteen months of age, most children can say eight to ten words. By age two, most are putting words together in crude sentences such as “more milk.” During this period, children rapidly learn that words symbolize or represent objects, actions, and thoughts. At this age they also engage in representational or pretend play. At ages three, four, and five, a child’s vocabulary rapidly increases, and he or she begins to master the rules of language.