Tom appeared on the sidewalk with a bucket of whitewash and a long­handled brush. He stopped by the fence in front of the house where he lived with his aunt Polly. He looked at it, and all joy left him. The fence was long and high. He put the brush into the whitewash and moved it along the top of the fence. He repeated the operation. He felt he could not continue and sat down.

    He knew that his friends would arrive soon with all kinds of interesting plans for the day.

    They would walk past him and laugh. They would make jokes about his having to work on a beautiful summer Saturday. The thought burned him like fire.

    He put his hand into his pockets and took out all that he owned. Perhaps he could find some way to pay someone to do the whitewashing for him. But there was nothing of value in his pockets—nothing that could buy even half an hour of freedom. So he put the bits of toys back into his pockets and gave up the idea.

    At this dark and hopeless moment, a wonderful idea came to him. It filled his mind with a great, bright light. Calmly he picked up the brush and started again to whitewash.

    While Tom was working, Ben Rogers appeared. Ben was eating an apple as he walked along the street. As he walked along it, he was making noises like the sound of a riverboat. First he shouted loudly, like a boat captain. Then he said “Ding－Dong－Dong”， “Ding－Dong－Dong” again and again, like the bell of a riverboat. And he made other strange noises. When he came close to Tom, he stopped.

    Tom went on whitewashing. He did not look at Ben. Ben stared a moment and then said: “Hello! I'm going swimming, but you can't go, can you？”

    No answer. Tom moved his brush carefully along the fence and looked at the result with the eye of an artist. Ben came nearer. Tom's mouth watered for the apple, but he kept on working.

    Ben said, “Hello, old fellow, you've got to work, hey？”

    Tom turned suddenly and said, “Why, it's you, Ben! I wasn't noticing.”

    “Say—I'm going swimming. Don't you wish you could? But of course you'd rather work—wouldn't you? Of course you would.”

    Tom looked at the boy a bit, and said, “What do you call work？”

    “Why, isn't that work？”

    Tom went back to his whitewashing, and answered carelessly.

    “Well, maybe it is, and maybe it isn't. All I know is, it suits Tom Sawyer.”

    “Oh come, now, you don't mean to say that you like it？”

    The brush continued tomove.

    “Like it? Well, I don't see why I shouldn't like it. Does a boy get a chance to whitewash a fence every day？”

    Ben stopped eating his apple. Tom moved his brush back and forth, stepped back to look at the result, added a touch here and there, and stepped back again. Ben watched every move and got more and more interested. Soonhe said，“Say, Tom, let me whitewash a little.”

    Tom thought for a moment, and was about to agree, but he changed his mind.

    “No—no—it won't do, Ben. You see, Aunt Polly wants this fence to be perfect. It has got to be done very carefully. I don't think there is one boy in a thousand, maybe two thousand, that can do it well enough.”

    “No—is that so? Oh come, now—let me just try. Only just a little.”

    “Ben, I'd like to, but if it isn't done right, I'm afraid Aunt Polly … ”

    “Oh, I'll be careful. Now let me try. Say—I'll give you the core of my apple.”

    “Well, here—No, Ben, now don't. I'm afraid …”

    “I'll give you all of it.”

    Tom gave up the brush with unwillingness on his face, but joy in his heart. And while Ben worked at the fence in the hot sun, Tom sat under a tree, eating the apple, and planning how to get more help. There were enough boys. Each one came to laugh, but remained to whitewash. By the time Ben was tired, Tom sold the next chance to Billy for a kite; and when Billy was tired, Johnny bought it for a dead rat—and so on, hour after hour. And when the middle of the afternoon came, Tom had won many treasures.

    And he had not worked. He had had a nice idle time all the time, with plenty of company, and the fence had been whitewashed three times. If he hadn't run out of whitewash, Tom would have owned everything belonging to his friends.

    He had discovered a great law of human action, namely, that in order to make a man or a boy want a thing, it is only necessary to make the thing difficult to get.

    On the day the tornado hit, there was no indication that severe weather was on its way—the sky was blue and the sun bad been out. The first alert my husband,Jimmy,67,and I,65,got came around 9 p.m., from some scrolling text on the TV Jimmy was watching. He ran upstairs to find me in our third-floor bedroom, and we changed the channel from the presidential primary debate I had been watching to our local Pensacola, Florida, station.

    No sooner had we found coverage of the tornado than it was on top of us. It was the loudest thing I have ever heard. The bones of the house shook, and the power went out. The wind began to roar through the house, most likely through blown-out windows and the door to our garage. We had three flights of steps to navigate to get to the relative safety of the first floor, because the cupboard down there is underneath a brick staircase.

    I didn't know how or if we would make it down the steps. It felt as if there were no floor underneath me as the wind lifted me off my feet. I tried to move forward, but this intense pressure held me in place.

    As we reached the last flight of steps, our front door blew out. Pieces of glass that looked like crushed ice flew everywhere. Suddenly, a three-foot-long tree branch crashed into the door frame. It flew over our heads, missing us by inches. Had we been one step up, it would have hit us.

    By the time I reached the cupboard, the tornado had been over us for about a minute. Jimmy pushed me down to the cupboard floor, but he couldn't get inside himself because of the wind. I held Jimmy's arm and tried to bring Jimmy with it. My knees were full of glass, but at that moment, I felt no pain. If I had let go, Jimmy would have flown right out the back of the house and into the bay.

    All of a sudden, Jimmy lifted off his feet like people in tornadoes do in the movies. I thought he was gone. And then everything stopped. He landed on his feet. In those first quiet moments, I couldn't believe it was over, Jimmy said he'd go outside to check. "No,"I said. "Don't leave me. Don't leave me."

    Our neighbor says the storm lasted four minutes. In that time, four of the twelve town houses in our unit were completely destroyed. Of the houses left standing, ours suffered the most damage. Amazingly, none of us were severely injured.

根据短文内容，选择最佳答案，并将选定答案的字母标号填在题前括号内。

    How are you and your family going to celebrate Earth Day? It's a great day to get outside and ride a bike, but there are other ways you could spend the day. Here are four books. You can learn more about the earth and the animals that make the world a special place to live in.

    The Busy Beaver, by Nicholas Oldland

    Beaver is very, very busy, and he doesn't always think carefully. As a result, he makes a mess of the forest and ends up in hospital. Finally, he realizes how careless he's been and decides to make things right when he returns to the forest.

    Lessons from Mother Earth, by Elaine Mcleod

    Five-year-old Tess is visiting her grandmother and, for the first time, she visits the garden. Along the way, Tess's grandmother tells her the rules of the garden, "You must always take good care of our garden. Never throw rubbish around. There is plenty for everyone to share if we don't destroy the soil." The story is beautifully told as a caring conversation between a child and her grandmother.

    Luz Sees the Light, by Claudia Davila

    When Luz's community(社区) experiences a series of black-outs(停电), she quickly comes to understand the need to save energy and find other ways of doing things. With the help of her friends and neighbors, she creates a community garden and park that everyone can use. The book attracts many young readers.

    The Lorax, by Dr Seuss

    A young boy learns of the role of the Lorax as protector(保护者) of the trees, and how his home became polluted. The book contains memorable forestry conservation (森林保护).

    In 2012 my wife and I decided to open our bookstore in spite of unfavorable situations. The challenges facing small bookstores were-and remain-significant. Apart from the obvious rise in online selling, the increase in the popularity of e-books has negatively affected independent providers.

    The question is why a new, small-scale（小规模的）provide would voluntarily enter such a challenging market? From a personal view, our reasoning was sound: we wanted to share our love of great books and reading for pleasure with as many like-minded people as possible.

    Having done our homework, one thing became clear. In order for us to succeed, we would have to offer something that none of our larger competitors already provided. And so we started the Willoughby Book Club. We set up our website in the summer of 2012, and we haven't looked back.

    The idea of service is simple. We offer a range of book subscription gift packages, available in three-month, six-month and 12-month options. Our customers choose a package, tell us a little about the person they're buying it for, and we use this information to send the receiver a hand-picked, gift-wrapped book once a month. We also recently decided to give one new book to Book Aid International for every gift subscription sold. These books are sent out to sub-Saharan Africa, supporting the educational work there. Within four months of starting out, we won the Young Bookseller of the Year Award at the 2013 Bookseller awards.

    Our brief journey from new booksellers to award receivers has been challenging and rewarding. The biggest thing we've learned is that, despite the pressures facing independent providers, there is a place for them in the UK market. It's just a question of finding it.

How to Prevent Dehydration

    When the weather's warm, you need to make sure you drink enough water. But did you know that you lose your sense of thirst as you get older? This means you5re more likely to become dehydrated, making you more prone to (有倾向) falls, heart disease, urinary-tract infections, kidney stones and confusion. A study from Loughborough University in the UK has shown that drivers who had only a little water an hour made twice as many mistakes as motorists who were properly hydrated. In fact, they made a similar number of errors to what you'd expect from someone over the drink-drive limit.

    So how do you know when you're dehydrated? Warning signs include:

    Feeling tired

    Dry mouth and dry skin

    Dark urine

    Reduced appetite (食欲)

    Reduced concentration

    Headache

    Constipation.

    But you might not notice any symptoms (症状)at all，so to make sure you stay hydrated:

    Keep a glass of water by your side when you're at home, and drink it regularly.

    Form a new drinking habit—for example, when watching TV, always reach for the water glass during an ad break.

    Take a small bottle of water with you when you go out.

    Always drink a large glass of water with a meal.

    Eat fruit and vegetables with high water content.

    Draw up a weekly water card—a bit like a coffee loyalty card—with a target of eight glasses of water a day. Mark it every time you have a glass of water. Award yourself a prize when ifs full at the end of the week.

    Drink water before, during and after you take any exercise.

Donna Strickland was awarded the 2018 Nobel Prize in Physics jointly with Arthur Ashkin and Gérard Mourou.It's the first time in 55 years that a woman has won this famous prize, but why has it taken so long? We look at five other pioneering female physicists — past and present — who actually deserve the prize.

Jocelyn Bell Burnell

Perhaps the most famous snub (冷落): the student Bell discovered the first radio pulsars in 1967, when she was a PhD student at Cambridge.The Nobel Prize that recognised this landmark discovery in 1974, however, went to her male supervisor, Antony Hewish.Recently awarded a £2.3 million Breakthrough Prize, which she gave away to help under-represented students, she joked to The Guardian, "I feel I've done very well out of not getting a Nobel Prize."

Lene Hau

Hau is best-known for leading the research team at Harvard University in 1999 that managed to slow a beam of light, before managing to stop it completely in 2001.Often topping Nobel Prize prediction lists, could 2019 be Hau's year.

Vera Rubin

Rubin discovered dark matter in the 1980s, opening up a new field of astronomy.She died in 2016, without recognition from the committee.

Chien-Shiung Wu

Wu's "Wu experiment" helped disprove the "law of conservation of parity".Her experimental work was helpful but never honoured, and instead, her male colleagues won the 1957 Nobel Prize for their theoretical work behind the study.

Lise Meitner

Meitner led groundbreaking work on the discovery of nuclear fission.However, the discovery was acknowledged by the 1944 Nobel Prize in Chemistry, which was won by her male co-lead, Otto Hahn.