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.

    We can achieve knowledge either actively or passively. We achieve it actively by direct experience, by testing and proving an idea, or by reasoning.

    We achieve knowledge passively by being told by someone else. Most of the learning that takes place in the classroom and the kind that happens when we watch TV or read newspapers or magazines is passive. Conditioned as we are to passive learning, it's not surprising that we depend on it in our everyday communication with friends and co-workers.

    Unfortunately, passive learning has a serious problem. It makes us tend to accept what we are told even when it is little more than hearsay (传闻) and rumor.

    Did you ever play the game Rumor? It begins when one person writes down a message but doesn't show it to anyone. Then the person whispers it, word for word, to another person. Thai person, in turn, whispers it to still another, and so on, through all the people playing the game. The last person writes down the message word for word as he or she hears it. Then the two written statements arc compared. Typically, the original message has changed.

    That's what happens in daily life. The simple fact that people repeat a story in their own words changes the story. Then, too, most people listen imperfectly. And many enjoy adding their own creative touch to a story, trying to improve on it, stamping it with their own personal style. Yet those who hear it think they know.

    This process is also found among scholars and authors: A statement of opinion by one writer may be restated as fact by another, who may in turn be quoted by yet another; and this process may continue, unless it occurs to someone to question the facts on which the original writer based his opinion or to challenge the interpretation he placed upon those facts.

    With five breakout(破纪录的) games, Jeremy Lin has become the NBA's newest star.

    In the New York Knicks' 92-85 won over the Los Angles Lakers last Saturday, Lin had a career-high 38 points. A day later, he led the Knicks to their fifth victory, 100-98 to Minnesota Timberwolves. In his previous games, Lin, 23, had 23 points against the Washington, 25 points against New Jersey and 28 against Utah in his first start.

    Lin is smart. Before graduating from high school in California, he had sent his application to all the Ivy League Schools(常青藤联盟). He only got into Harvard and Brown, and he chose Harvard. In 2010, Lin graduated with a degree in economics.

    Lin is the first Chinese-American player in the NBA. He was born in the US and his family is Asian. Although not born in China, Lin has attracted nearly all Yao Ming's old fans, who see him as a powerful role model.

    He started off on the Golden State Warriors. Lin first signed with the Warriors in July, 2010, but seldom played in games before the start of the fourth quarter. His first time on the court for the Warriors earned him seven points, three rebounds(篮板球) and two assists in just 11 minutes.

    He is really perfect for the Knicks. The New York Knicks has been in need of a reliable point guard and to Mike D'Antoni, the Knicks coach who's going through a difficult season, Lin is a most unexpected figure. Lin just does everything easy and the rest of the guys around him are playing the way we want to," D'Antoni said. "I think it's for real, and it can only get better."

    As children we are well-trained to find the right answer. We are rewarded for A's, the honor roll and acing the test. Our education trains us to follow the rules and deliver the expected answers. When we do, awards and congratulations follow. Yet when we grow up, it gets a little harder. Life and careers don't have tests with an A if we get the "right" answer.

    I recently had coffee with a college student who will graduate. She is struggling with what she wants for her career. She wants her parents to be proud of her and to continue the success she has had in school. She also talked about other students in her graduating class who are set to do "some big things," like working for impressive companies. Yet she wasn't sure of the right answer for using her degree. She said that deep down she was hoping that someone might give her the answer.

    We both agreed that it comes down to not looking for the right answer, but her answer. The grown-up definition of the "right answer" is different than that in school. What would you do if you weren't afraid? It takes time to know these answers. And they can change over time and at any point in your career. My encouragement is to get valued advice and input, of course, but finally to look within yourself for the answers. It helps to come back to:

What do I want to be known for? What is my definition of success? What am I best at?

    If I had no fears, what would I do?

    What is one step I can take today to move me toward my goal (even if it's not perfectly clear)?

    I find these types of questions are more helpful at getting to our unique answer rather than "right answer" questions, such as: What will my parents want? What degree or job will mark me as accomplished to the world? What is my best option based on where I work today?

    When athletes at the 2020 Tokyo Olympics collect their medals, they'll not only be wearing something that celebrates their sporting performance, but something that symbolizes lastingness. For both the 2020 Olympics and Paralympics, organizers aim to make all of the gold, silver, and bronze medals out of used electronics. This strong message about how to make use of e-waste has gotten a lot of Japan involved.

    Starting in April 2017, the Japanese Olympic Committee began collecting old laptops, digital cameras, smartphones, and other abandoned electronics. The initiative(倡议)has achieved great  success. Already, the quantity needed for bronze medals has been met, and they're in the homestretch for silver and gold medals, meaning the collection process can pack up at the end of March.

    When looking just at the number of cell phones collected, the amount of waste is shocking. In a period of about 18 months, a little over 5 million smartphones were collected thanks to cooperation with NTT DOCOMO.

Japan's largest mobile phone operator allowed the public to turn in phones at their shops, which counted a lot in the project's success.

    After being taken apart and sorted, the small electronics underwent a smelting process to extract(提炼)all the gold, silver, and bronze elements. Thanks to this initiative, the worldwide struggle with e-waste will have a global platform. According to a study published by the United Nations University—44.7 million metric tons of e-waste were made in 2016. Only 20% of that was actually recycled. Unfortunately, this figure is set to rise significantly in the coming years, moving to 52.2 million metric tons by 2021. So while the Tokyo Olympics initiative might be just a drop in the bucket, it's a good start in showing what the public can do if they're made more aware of the issue.

Pick up any packaged processed food, and there's a decent chance that one of its listed ingredients will be "natural flavour". The ingredient sounds good, particularly in contrast to "artificial flavours" since there is a common belief that ingredients from nature are necessarily safer than something artificially made. But it's not true. Then what exactly does the natural flavour mean? It refers to extracts (提取物) got from natural sources like plants, meat or seafood. When consumers see the "natural flavour" on a label, they are unlikely to assume that someone is squeezing the juice from oranges into their bottles. They know even though natural flavour must come from natural sources, it needn't all come from the plant or meat. For example, orange flavours might contain not only orange extracts, but also extracts from bark and grass.

So if flavours like orange are needed, why not just use oranges? The answer comes down to "availability, cost, and sustainability", according to flavour chemist Gary Reineccius of the University of Minnesota. "If you're going to use all your grapes on grape soda," Reineccius says, "you don't have any grapes for wine making; the products are going to be exorbitant; besides, what do you do with the by-products you create after you've squeezed all the juice out of the grapes?"

Actually, while chemists make natural flavours by extracting chemicals from natural ingredients, artificial flavours are made by creating the same chemicals artificially. The reason why companies bother to use natural flavours rather than artificial flavours is simple: marketing. "Many of these products have health titles," says Platkin, professor from Hunter College. "Consumers may be talked to believe products with natural flavours are healthier, though they are nutritionally no different from those with artificial flavours. Natural flavours may involve more forest clear-cutting and carbon emissions from transport than flavours created in the lab."

Platkin suggests getting more transparent (易懂的) labeling on packaging that describes exactly what the natural or artificial flavours are, so consumers are-not misled into buying one product over another because of "natural flavours". Reineccius also offers simple guidance: "Don't buy anything because it says ‘natural flavours'. Buy it because you like it."