Taking a math test can be pretty stressful. Even if you know the material, you can still get the problem wrong. {#blank#}1{#/blank#} Therefore you'll improve your grades, as well as your math skills.

    Write it out

    You can also check a math problem by writing everything out on paper. {#blank#}2{#/blank#} Writing out math problems reduces your chances of missing anything to the lowest possible level, which is a common cause of incorrect answers.

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    Make sure your answers work by doing the opposite procedure of what your problem calls for, including the answer you got the first time around. In other words, you would use the opposite of this addition problem—subtraction (减法)—to determine whether your answer is the correct one.

    Plug in（代入）

    You may find that a variable isn't good enough or have a problem where you have to solve for a variable (变量). {#blank#}4{#/blank#} This is the only real way to assure yourself that the answer you've found is correct.

    {#blank#}5{#/blank#}

    If the result of a problem seems to make no sense, it indicates that the answer is incorrect. For example, if you get an answer in the millions and you know it should be in the thousands, you've likely misplaced a point. Go back through the work on your paper to make sure all of your formulas and calculations are correct. If everything looks okay, do the problem again and compare the result of the second try to what you've got on the first try.

A. Do the opposite.

B. Correct the answers.

C. Plug the variable in the equation (方程) to check it out.

D. Knowing how to go through your math test and checking your work can save you from handing in a test full of mistakes.

E. It also helps you to figure out everything after you have already finished the test.

F. Check for a reasonable answer

G. This helps you to know what information you have and what information you need to solve.

    Buy One Give One

    Buy One Give One (BIG1) is a Singapore-based business and non-profit organization with a job to create a world full of giving. We help businesses around the world give back in meaningful ways so that they can create measurable and long-lasting influence. Since 2007, we have worked with more than 1,600 businesses creating more than 88 million giving activities.

    Our business allows consumers, who may feel disconnected from the problems of the developing world, to become involved in social problems while still purchasing (购买)tor themselves. For example, shoe brands like TOMS promise to donate one pair of shoes for every pair purchased. Soapbox gives soap to a needy child with every purchase. Watch company WeWood plants a tree every time you buy a watch. They have helped socially-conscious consumers purchase products and feel good about providing help to others.

    See what some of our members say about being a part of BIG1.

    *Karen Ormerod

    Every product purchased at our store influences the lives of disadvantaged people in the world. I had never imagined I would be operating a business that could change people's lives. We are making a real difference by just doing what normally do. It is a wonderful experience.

    *Ben Baker

    What a good way of giving resources to where they need to be giving people the gifts of giving, and adding value to organizations along the wav. We have already made 160,000 giving activities through BIGI. Giving has become a necessary part of our everyday business. It's truly brilliant.

    BIGI focuses on the influence of giving on people's lives rather than simply the amounts donated. Our programs stress giving habitually in order to create growing influence around the world. When you join the BIGI giving program, you create your own unique giving stories.

    We do hope you can become a member of us!

    It's the holiday season, the time when we connect with family and friends. Social media sites like Twitter and Facebook are full of festive pictures, featuring parents' catching and sharing those special family moments, their child's wish list, and maybe even a cute video of their child dancing to “Jingle Bell Rock” while wearing a diaper (尿片) and Santa hat. Swelling with pride, parents can't wait to get approval with a “thumbs up” or better yet a personalized message on their treasured post.

    Adults should be able to post what they want online. However, when exposing family moments online, are they sharing too much information? Do parents have the right to share those cute now, but embarrassing later moments about kids? Have children willingly given their agreement to sharing their cute but funny video online?

    A recent study found that 75% of parents turn to social media for parenting-related information and social support. There is even a term used to describe the overuse of sharing too much information about kids on social media: “sharenting”. Research also finds that “sharenting” isn't going anywhere anytime soon. What's troublesome is that a typical parent has about 150 Facebook friends and only a third of them are actual friends. So that brings up good questions – Who are we really sharing our information with and why? Who knows when and where that photo could resurface in the future?

    While there's no reliable information on how young children feel about things posted online, we do have information about how teens feel. According to a report by the Family Online Safety Institute, 76% of teens are concerned about their privacy. Many teens constantly search for new apps that allow anonymity. When names are required, they use screen names that don't reveal real information. If our teens are doing a better job of protecting themselves online, shouldn't parents take the lead and do the same? Plus, with more and more college admission representatives and potential employers surfing the internet for potential candidates, we'd hate for one of our posts to change an important decision. Think about it … online reputations are now becoming inseparable with real life ones.

    Of course, we can secure our privacy settings, only allowing our friends to view pictures, posts and videos, but that doesn't stop others from uploading our pictures. Adults need to be cautious of sharing information online, especially information about children.

    So, this holiday season, enjoy family time and share those special memories with family and friends. Before clicking the app to upload photos or videos, stop and think twice.

    Imagine, one day, getting out of bed in Beijing and being at your office in Shanghai in only a couple of hours, and then, after a full day of work, going back home to Beijing and having dinner there.

    Sounds unusual, doesn't it? But it's not that unrealistic, with the development of China's high-speed railway system. And that's not all. China has an even greater high-speed railway plan to connect the country with Southeast Asia, and eventually Eastern Europe. China is negotiating to extend its own high-speed railway network to up to 17 countries in 10 to 15 years, eventually reaching London and Singapore.

    China has proposed three such projects. The first would possibly connect Kunming with Singapore via Vietnam and Malaysia. Another could start in Urumqi and go through Kazakhstan and Uzbekistan, and possibly to Germany. The third would start in the northeast and go north through Russia and then into Western Europe. The new system would still follow China's high-speed railway standard. And the trains would be able to go 346 kilometers an hour, almost as fast as some airplanes. Of course, there are some technical challenges to overcome. There are so many issues that need to be settled, such as safety, rail gauge(轨距), maintenance of railway tracks. But the key issue is really money. China is already spending hundreds of billions of yuan on domestic railway expansion.

    China prefers that the other countries pay in natural resources rather than with capital investment. Resources from those countries could stream into China to sustain development. It'll be a win-win project. For other countries, the railway network will definitely create more opportunities for business, tourism and so on, not to mention the better communication among those countries.

    For China, such a project would not only connect it with the rest of Asia and bring some much-needed resources, but would also help develop China's far west. We foresee that in the coming decades, millions of people will migrate to the western regions, where the land is empty and resources unused. With high-speed trains, people will set up factories and business centers in the west once and for all. And they'll trade with Central Asian and Eastern European countries.

    Is it wrong—either grammatically or in terms of style—to mix the simple past tense with the past perfect in one sentence? To give an example, the following seems a bit heavy and awkward to me: "There had been a time when she had been happier.' I prefer: 'There had been a time when she was happier.' Any thoughts?

—ALEX

I think the second version is the correct one—it's shorter and clearer. Rather than focusing on tenses, focus on the clean, short sentence. If something seems heavy and awkward to you, the writer—then it probably is. Always short sentences.

—DIANA

    I have constructed texts for a range of children's picture books all based on working profession: bus driver, postman, footballer, cleaner, teacher, policeman to list a few. I've listed about thirty professions so far. I thought of titling them as Mr Bus Driver, Mr Postman and so on. Would I be infringing (侵权) the Mr Men titles if I did or should I think of something else?

—RAJIV

    The Mr Men stories are based on characteristics, not on jobs—Mr Lazy, Mr Noisy, etc—so they bear no relation to your projects. However, you will come under fire from gender equality supporters—every job you list could equally be done by a woman. No teacher and few parents would find work useful if it implies that all professions are open only to men. I advise you to look at modern children's books in a library or bookshop.

—DIANA

    "I really wrote it for me. It was what I found funny and what I liked". Those are the words of J K Rowling, author of the enormously popular "Harry Potter" books. The quote refers to the first in a series of novels featuring a young character who has carved out a permanent place for his creator in the world of children's literature.

    Joanne Kathleen Rowling was born in England in 1965, and wrote her first story at the age of six. She was in her mid-20s when the idea for the Harry Potter novels came to her, during a long train ride. By the end of that journey, she says, the character of Harry and the school for wizards which he attends were more or less fully formed in her mind.

    It would be several years, however, before the novel was completed. By that time, Rowling had been through a failed marriage. Living on welfare as a single parent, she wrote about Harry Potter while sitting in an Edinburgh café with her daughter asleep beside her. She could not have dreamed of the fame and success which Harry would bring her in the years to come.

    Harry Potter is not your average superhero. He is 12 years old, skinny, wears glasses, and tends to worry a lot. Yet, he has captured the imagination of children and adults the world over, and has introduced millions to the joys of reading.

    Harry's appeal stems from his role as a very ordinary boy who finds himself in extraordinary situations. Orphaned as a baby, Harry spends the next 10 years being mistreated by the awful relatives with whom he lives. On his 11th birthday, he learns that he possesses magical powers and is admitted for training at the Hogwarts School of Witchcraft and Wizardry.

    The adventures of Harry and his friends at the school are superbly narrated by J. K. Rowling. She manages to lead her millions of readers deep into the world of the supernatural, while at the same time dealing with the fears and emotions of the ordinary human world. Many feel that this is the real magic of Harry Potter.