As global temperatures continue to rise, more “extreme rain” events—intense, cats-and-dogs down pours—can be expected, said the study, published Monday in the journal Nature Climate Change. And that, scientists said, means an increased flood risk, particularly for the world's driest areas. The study challenges the idea that global warming is causing dry areas to become drier and wet areas wetter.

    “In both wet and dry regions, we see these great increases in heavy precipitation（冰雹）,” lead author Markus Donat, a climate scientist at the University of New South Wales, told Nature.

    Donat and his team collected data from 1951 to 2010 on extreme precipitation events from 11, 000 weather stations around the world, Nature reported.

     In that time, the number of days with“extreme precipitation” increased 1 percent to 2 percent per decade.

  “We found a strong relationship between global warming and an increase in rainfall, particularly in areas outside of the tropics,” Donat said in a statement.

  “Importantly, this research suggests we will see these extreme rainfall events increases at regional levels in dry areas, not just as an average across the globe,” Donat added.

    Peter Stott, a senior climate scientistat Met Office, told Climate Central that the study's findings are important, because more violent rainfall and flooding will “challenge our capability toadapt to a rapidly changing climate.”

    As Nature reported, the researchaligns（结盟）with a 2015 study that found global warming has led to a sharp increase in record-breaking precipitation events. Donat told Nature that his study should come as a warning to world governments.

阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。

    In the tenth grade，I began working for free at a vet's that was run by a friend. I wanted to get experience for what I thought would be my future job. However，on one particular Saturday morning I learnt something perhaps more important.

    The hospital was in the middle of one of the poorer sections of the city and some people could only pay for the most basic treatments. On this Saturday，a man and his young son，who was probably about 7 years old，walked in with a small cat in a cardboard box. There was something wrong with the cat's left eye. But the man could not afford to pay for the cost of the medicine. He kept quiet for a while，and then he asked where the nearest animal shelter was. Hearing this，his son cried and started to argue with him. All of a sudden，an older woman who was sitting in the waiting room stood up，walked up to the counter，and told the man that she would pay for the cost. The man thanked her and the son got to keep a healthy cat.

    I always thought it was the right thing to help out a needy person，but I only saw people do acts of kindness on TV or in movies. What the woman did made me believe that these things do happen in real life，and quite often.

Now，when I can't decide whether to help someone who is in need，I remember this woman，and then I have the courage to step up to the plate. Sometimes other people follow.

    A young woman carrying a three-year-old child got on a bus. The conductor hurried to give her a warm welcome and then kindly asked the other passengers to make more room for the woman and her kid. On seeing this, people were surprised and began to talk." You know this conductor used to be very rude. Now suddenly he has changed his bad behavior, "said a middle-aged man.

    "Yes, he should be praised and we must write a letter to the company," said a second passenger." That's right," another lady said, "I wish a newspaper reporter were here so that more people could learn from this conductor."

    Just then a gentleman who looked like a teacher turned to the conductor and said, "Excuse me, but can I know your name, please? Your excellent service must be praised…"

    Before he could open his mouth, the three-year-old kid sitting on the young woman's lap interrupted, "I know his name; I call him Dad."

    Women may have good reason to drink coffee as much as they like. According to recent research, women who drank three or more cups of coffee a day were 30 percent less likely to have memory decline at age 65 than whose who drank one cup or less daily. And the benefit increased with age. Women over age 80 who drank three or more cups of coffee a day were about 70 percent less likely to have memory decline than those who drank one cup or less, the researchers said.

    Caffeinated tea had the same effect in the women, the study found, although more was needed to get the same caffeine boost. "Count roughly two cups of tea for a cup of coffee," said study leader Karen Ritchie of INSERM, the French National Institute for Health and Medical Research.

    But the researchers didn't find a similarly protective effect in men, although other studies have found a benefit to males.

    How might caffeine help ward off cognitive decline? "It is a cognitive stimulant." said Ritchie. "It also helps to reduce levels of the protein called beta amyloid in the brain" she said, "whose accumulation is responsible for Alzheimer's disease but which also occurs in normal aging."

    Ritchie said she wasn't sure why men in the study didn't benefit from caffeine. "Our hypothesis is that either women metabolize caffeine differently than men, or there may be an interaction of the caffeine with the sex hormones," she said.

    The French study confirms previous research, said William Scott, professor of medicine at the University of Miami Miller School of Medicine, who has researched caffeine's beneficial effects against Parkinson's disease, also a neurodegenerative disorder.

    As for caffeine only protecting women, Scott noted that just 2,800 of the 7,000 study participants were men, and the results might have differed if more men were included.

    A study published in February in the European Journal of Clinical Nutrition looked at 676 healthy men and found that regular coffee drinkers had a lower rate of cognitive decline over a 10-year follow-up than those who didn't drink coffee. Those who drank three cups daily had the least signs of decline.

    Both Scott and Ritchie agreed that more study is needed. Ritchie's research will next look at the relationship between caffeine and Alzheimer's.

An Edinburgh inventor has created a fully biodegradable bottle that is made from paper and a secret combination of plant materials, and it could help save the planet's oceans from plastic pollution and can also be eaten by sea creatures.

The Edinburgh-based Durham University chemistry graduate James Longcroft started a non-profit bottled water company two years ago. He wanted to put all his profits into a charity that provided clean drinking water to countries in Africa.

However, after concerns about the environmental impact of plastic bottles, Mr. Longcroft decided the Edinburgh and London-based company, Choose Water, should go plastic-free. So he came up with a new type of water bottle—a waterproof paper bottle.

"The outside is made from recycled paper, but the inside has to be waterproof, and provides strength so the bottle would keep its structure, and keep the water fresh," Mr. Longcroft said.

When the bottle is thrown in the ocean the degrading process begins within hours leaving the bottle totally degraded (分解)within weeks. The steel cap breaks down within a year.

Mr. Longcroft now believes these novel bottles could revolutionise the industry and says the cost of producing the bottle is around 5 pence more than one made from single-use plastic.

"The main difficulty we face is breaking into a saturated (饱和的)market and competing with an old industry," he said. "Changing an industry will be a big uphill battle, but with the support from the public, we will change the way we look at bottled water."

Researchers warn that eight million tonnes of plastics currently find their way into the ocean every year which will stay in the environment for centuries.

"We really want to get our bottles on shelves and into people's hands as soon as possible—if we can stop even one plastic bottle ending up in the environment it will be worth it," said Mr Longcroft.

The periodic table of elements is a common sight in classrooms，campus hallways and libraries. The mode periodic table arranges the elements by their atomic numbers and periodic properties（周期性）. Several scientists worked over a century to assemble the elements into this format. 

In 1789，French chemist Antoine Lavoisiertried grouping the elements as metals and nonmetals. Forty years later，German physicist Johann Wolfgang Dobereiner observed similarities in physical and chemical properties of certain elements. He arranged them in groups of three in increasing order of atomic weight and called them triads，observing that some properties of the middle element，such as atomic weight and density，approximated the average value of these properties in the other two in each triad. 

A breakthrough came with the pu blication of a revised list of elements and their atomic masses at the first international conference of chemistry in Karlsruhe，Germany，in 1860. They concluded hydrogen would be assigned the atomic weight of 1 and that the atomic weight of other elements would be decided by comparison with hydrogen. For example，carbon，being 12 times heavier than hydrogen，would have an atomic weight of 12. 

In 1869，Russian chemist Dmitri Mendeleev created the framework that became the moder periodic table，leaving gaps for elements that were yet to be discovered. Mendeleev predicted the properties of some undiscovered elements and gave them names such as"eka-aluminum"for an element with properties similar to aluminum. Later "eka-aluminum"was discovered as gallium. 

German chemist Lothar Meyer produced a version of the periodic table similar to Mendeleev's in 1870. He left gaps for undiscovered elements but never predicted their properties. The Royal Society of London awarded the Davy Medal in 1882 to both Mendeleev and Meyer. The later discovery of elements predicted by Mendeleev verified（证实）his predictions and his periodic table won universal recognition. In 1955 the 101st element was named mendelevium in his honor. 

On UNESCO website，it wrote，"The Periodic Table of Chemical Elements is more than just a guide or catalogue of the entire known atoms in the universe；it is essentially a window on the universe，helping to expand our understanding of the world around us. "