Sleep is something we all do. But some people need to sleep more than others. Babies sleep most of the time. Children in school sleep about ten to twelve hours a night. Most adults sleep only seven or eight hours. {#blank#}1{#/blank#}

    All parts of our bodies have to rest after they work.. Our arms need a rest after we lift heavy thing, When we run fast, our legs work hard. They get tired. We have to rest them. Our brains work hard, too. {#blank#}2{#/blank#}. We can sit quite still and rest our arms and legs. But our brains aren't resting. They go right on thinking as long as we are awake.

    Our brains slow down a bit when we sleep and dream. {#blank#}3{#/blank#} Instead of thinking wide-awake thoughts, our brains make up dreams. Some dreams are very pleasing. Some are not. Most of the time we forget them when we wake up.

    Scientists have tried to find out what would happen if people were not allowed to sleep. They asked some people not to go to bed. The people stayed up all night and all the next day. They stayed up the next night too, and the day after. They played games, but they made mistakes. They forgot things. {#blank#}4{#/blank#}

    The people grew rude and mean. They became angry with their friends. Finally they were too tired to stand up. When they sat down, they fell asleep.

    Scientists have found that if people are not allowed to sleep and to dream, they act in an unusual way. {#blank#}5{#/blank#} But we do know that we need it to stay well. So tonight have a good sleep. Lie down under the covers. Shut your eyes. Let your thoughts wander. Soon you'll stop thinking. You'll be asleep.

A. It was hard for their tired brains to work.

B. When we are awake, they help us pay attention to the world around us.

C. But babies, children, and adults — all of us need to have our sleep.

D. Good sleep helps to improve one's memory.

E. No one knows why sleep is so good for us.

F. But even as we sleep our brains are doing some work.

G. Of course you will have a good sleep.

How did the ancient Chinese keep food warm in winter?

    Facilities like electric rice cookers, microwaves, and electric kettles, make it easy for people to keep food warm and enjoy a comfortable winter. So how did Chinese people in ancient times keep food warm in winter without these? In fact, ancient Chinese people used their own methods of heat preservation as early as the Shang and Zhou dynasties.

● “Wen Ding”, ancient rice cooker

    One of the major functions of an electric rice cooker is to keep food warm. The “Wen Ding”, an ancient cooking container, served the same purpose, but instead of using electric energy, the ancient cooking container, served the same purpose, but instead of using electric energy, the ancient cooking container preserved heart by burning fuels like charcoal.

    The “Wen Ding” unearthed in Nanjing in 1989 is thought to be the oldest of its kind discovered in China, dating back to the Stone Age, The craftsmanship of making the “Wen Ding” was developed in the Bronze Age. The bronze Ding from Shang and Zhou dynasties took on different shapes and structures.

● “Ran LU”, ancient small hot pot

    The “Ran LU” is a small size cooking vessel(器皿) made of bronze, which can be divided into three parts. A charcoal stove forms the main structure, with a bottom tray to hold charcoal ashes, and a movable cup at the top. Some experts have concluded that the vessel's structure suggests it may have been used as a small hot pot and that these vessels became popular in the Warring States Period(475—221 BC)

●Bronze You, ancient kettle

    The Bronze You was one of the most common wine containers during the Shang and Zhou dynasties. The Bronze You can also be used to warm wine. For example, the Bronze You with beast mask design, unearthed in Jiangxi province, has an opening where charcoals could be placed. Just as people today can't do without an electric kettle, the Bronze You allowed people to enjoy a hot drink.

●Bronze Yan, ancient steamer

    Although the “Wen Ding” was effective at keeping food warm, the ancient Chinese people later found that its burning produced pollution. As a result, the Bronze Yan was made with a two-tier structure and used to steam rice and other grains. After the Eastern Han Dynasty (AD 25-AD 220), further improvements to the Bronze Yan led to the modern-day steamer.

    It may appear strange to hear that crops are making headlines.But this is no ordinary produce—these fruits and vegetables have been grown in simulated（模拟的）Martian and lunar soils!

    Though the possibility of growing crops in outer space only gained widespread interest after Matt Damon grew potatoes in the movie "The Martian",scientists have been testing the idea for many years.Fresh produce will after all be the key to setting up space colonies（殖民地）.

    Among the pioneers in this effort is a team led by Wieger Wamelink,a scientist at Netherland's Wageningen University.In 2013,they planted fourteen varieties of plants in simulated Martian and lunar soils.Though the "Mars" plants did not bear any produce,they grew better than the "lunar" plants,most of which died shortly after being planted.Lack of vapor in the soil,according to the scientists,might have accounted for the failure.

    The second experiment began in late 2015.The researchers selected the same crops,while this time they used larger containers and added grass to them.In March 2016,their efforts were rewarded with a variety of produce including the vegetable that kept "The Martian" alive: potatoes.

    However,the researchers were still not sure if the produce was safe to eat.That's because the Martian and lunar soils contain heavy metals like lead and arsenic,which do not affect plants but are poisonous to humans.

    After months of testing,earlier this week,the team finally confirmed that the produce was safe for human consumption.Some of the crops even contained lower levels of heavy metals than plants grown in the "ordinary" earth soil.

    To celebrate the success,the scientists held a dinner party that centered ground the crops.While there is no word on how the food tasted,it sure looks delicious.

    Have you ever learned about F. Scott Fitzgerald? F. Scott Fitzgerald, born on September 24, 1896, an American novelist, was once a student of St. Paul Academy, the Newman School and attended Princeton. University for a short while. In 1917 he joined the army and was posted in Alabama, where he met his future wife Zelda Sayre. Then he had to make some money to impress her.

    His life with her was full of great happiness, as he wrote in his diary:" My own happiness in the past often approached such joy that I could share it even with the person dearest to me but had to walk it away in quiet streets and take down parts of it in my diary."

    This side of paradise, his first novel, was published in 1920. Encouraged by its success, Fitzgerald began to devote more time to his writing. Then he continued with the novel the Beautiful and Damned (1922), a collection of short stories Thales of the Jazz Age (1922), and a play The Vegetable (1923). But his greatest success was The Great Gatsby, published in 1925, which quick brought him praise from the literary world. Yet it failed to give him the needed financial security. Then, in 1926, he published another collection of short stories All the Sad Young Men.

    However, Fitzgerald's problems with his wife Zelda affected his writing. During the 1920s he tried to reorder his life, but failed. By 1930, his wife had her first breakdown and went to a Swiss clinic. During this period he completed novels Tender Is the Night in 1934 and The Love of the Last Tycoon in 1940 while his wife was in hospital in the United States, he got totally addicted to alcohol. Sheila Graham, his dear friend, helped him fight his alcoholism.

    Many people believe high heels(E)make women look good. It seems that the organisers of the Cannes Film Festival reportedly stopped women in low-heeled shoes from walking the red carpet. But all this charm comes at a cost, wearing heels over 10em high can damage your feel.

    A study by Hanseo University in South Korea suggests that continuous wearing makes women run the risk of getting hurt, and makes them easy to lose their balance, A total of 40 women who wear high heels at least three times a week took part in the study, The strength of their feet was measured regularly, researchers found that two of the four main muscles became stronger after a period of between one and three years, This created an imbalance in their feet, Dr Yong Seok Jee from Hanseo University says that the habit of wearing heels can result in feet out of shape, back pain and unhealthy walking patterns He suggests that women limit the use of these kinds of shoes and exercise their foot muscles properly.

    High heels are considered by some people to be female, but in fact the fashion started with men's feet. These shoes were a form of riding footwear, and were seen on the feet of 17th century Persian soldiers, Elizabeth Semmelhack of the Bata Shoe Museum in Toronto says: “When the soldier stood up in his stirrups (马镫), the heel helped him keep balance so that he could shoot more effectively.

    Before becoming a main part of modern women's clothing, high heels were used by Louis XIV of France. These shoes were status (身份) symbols Lets face it-nothing shows off status like uncomfortable, expensive and impractical clothing. They say the wearer doesn't have to work in fields or walk very far.

D

With the completion of the Human Genome（基因组）Project more than 20 years ago, and the discovery of the double helix structure of DNA enjoying its 70th birthday last year, you might assume that we know how life works. Think again!

Evolution has a 4bn-year head start on us. However, several aspects of the standard picture of how life works-the idea of the genome as a blueprint, of genes as instructions for building an organism, of proteins as precisely tailored molecular（分子）machines and more-have wildly reduced the complexity of life. 

In the excellent book How Life Works, Philip Ball explorers the new biology, revealing life to be a far richer, more delicate affair than we have understood. Ball explains that life is a system of many levels-genes, proteins, cells, tissues, and body modules-each with its own rules and principles, so there is no unique place to look for an answer to it. 

Also, How Life Works is a much more appealing title than the overused question of "What is life?". We should be less concerned with what a thing is, and rather more focused on what a thing does. Defining a living thing implies an unchangeable ideal type, but this will run counter to the Darwinian principle that living things are four-dimensional, ever changing in time as well as space.

But it's an idea that is deeply rooted within our culture. Ball points out that we rely on metaphors（比喻）to explain and explore the complexities of life, but none suffice. We are taught that cells are machines, though no machine we have invented behaves like the simplest cell; that DNA is a code or a blueprint, though it is neither; that the brain is a computer, though no computer behaves like a brain at all.

Ball is a terrific writer, pumping out books on incredibly diverse subjects. There's a wealth of well-researched information in here, and some details that are a bit chewy for the lay reader. But the book serves as an essential introduction on our never-ending quest to understand life.