Energy independence. It has a nice ring to it. Doesn't it? If you think so, you're not alone, because energy independence has been the dream of American president for decades, and never more so than in the past few years, when the most recent oil price shock has been partly responsible for kicking off the great recession.

    “Energy independence” and its rhetorical (修辞的) companion “energy security” are, however, slippery concepts that are rarely though through. What is it we want independence from, exactly?

    Most people would probably say that they want to be independent from imported oil. But there are reasons that we buy all that oil from elsewhere.

    The first reason is that we need it to keep our economy running. Yes, there is a trickle（涓涓细流）of biofuel available, and more may become available, but most biofuels cause economic waste and environmental destruction.

    Second, Americans have basically decided that they don't really want to produce all their own oil. They value the environmental quality they preserve over their oil imports from abroad. Vast areas of the United States are off-limits(禁止) to oil exploration and production in the name of environmental protection. To what extent are Americans really willing to endure the environmental impacts of domestic energy production in order to cut back imports?

    Third, there are benefits to trade. It allows for economic efficiency, and when we buy things from places that have lower production costs than we do, we benefit. And although you don't read about this much, the United States is also a large exporter of oil products, selling about 2 million barrels of petroleum products per day to about 90 countries.

    There is no question that the United States imports a great deal of energy and, in fact, relies on that steady flow to maintain its economy. When that flow is interrupted, we feel the pain in short supplies and higher prices, At the same time, we derive(得到，获得) massive economic benefits when we buy the most affordable energy on the world market and when we engage in energy trade around the world.

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。

    Actually, long-distance bicycle camping is one of the most pleasurable activities I have ever experienced.

    I generally sleep poorly at night, but in the woods on a tour, I sleep like a baby, falling asleep with the music of insects. In the morning, I am awakened by the cheeps of birds. I eat a snack before getting up, and then I quickly pack my sleeping bag, air mattress (垫), tent, and other things and get on with my road. I'm slower in the morning, having less speed but a greater desire to stop at pleasant spots and enjoy the beautiful scenery. Traveling by bike allows me to stop anywhere, such as grasslands, lakes, woods, and scenic spots. Near lunch, I find a small grocery and buy some bread, sandwiches and fruit. Then I will find a town park or other shady spots to wait out the high mid-day sun. In the afternoon, my speeds are higher, and I spend less time on stops. In the late afternoon, I start riding more slowly, and I start thinking about where I will stop. I finally find a place in the early evening, cook a simple meal and have a rest. As it starts to get dark, I put up my tent, crawl in and fall asleep.

    There are exciting times and difficult times as well. Visiting strange or famous places and accomplishing goals are always exciting to me. I meet and talk with interesting people along the way, sometimes other traveling cyclists. Appreciating beautiful views, meeting wild animals, and traveling up and down hills also. On the other hand, I may run into a rainy or hot spell(一段时间), have to repair my bike, or just find myself in a bad mood. The problems are infrequent and are easy to deal with. The pleasures remain in my mind for years.

With the clicking of walking sticks and determined steps, a long line of walking group along the winding road is a fantastic sight. Almost each of the walkers is using some kind of fitness tracker. A few Fitbits, some Xiaomi wrist bands (手环), a couple of phone apps and some other pedometers (计步器) — and all, they say, are counting their steps.

    Fitness trackers are in. Sales figures for 2016 released by Internet Data Center (IDC) indicated 25% market growth compared to the previous year, with Fitbit taking the lion's share, followed by the brand Xiaomi.

    However, the wearables market has had a rollercoaster ride in recent months. Jawbone, once a popular fitness tracker brand, announced that it is leaving the consumer market. Microsoft has removed its Fitness Band on its online store although it is still available on retail (零售) giant Amazon. Fitbit remains a key brand name at the heart of the fitness tracker revolution. But it is recently reported to be cutting down on workers, and its founder James Park said it experienced “softer than expected” sales recently.

    Counting steps is probably the most common use of wearable devices (可穿戴设备), but recently experts have questioned whether the golden goal of walking 10,000 steps a day is actually worthwhile, and a US study concluded that health trackers did not aid weight loss.

Analyst Ben Wood from CCS Insight used to wear a fitness tracker on either wrist. Now, however, his concern is about users'experience — these devices don't tell you anything new after a while. There are also battery problems and many of the older and cheaper varieties aren't waterproof (防水的).

    My first book had been rejected by every major American publisher. My first agent, wasn't communicating. My dream of a life as a successful author was in tatters.

"It isn't going to happen," I said to my friend. "And I have to accept it."

"If you lose faith in your product, no one else will have faith in it," she told me.

    And, I knew she was right. But, how could I believe in myself when I hit a wall at every turn? I knew I had a good product. The book featured interviews with world-famous people who had learned how to succeed and lead—the hard way. It had information that could help other people. As a consumer, I would have loved that book because it had the great wisdom I so desperately needed. And, their stories made for good reading. I had a good book. What I didn't have was a publisher. I had to find a way to get that book sold and on the shelves. But, how?

    The hardest challenge was forcing myself to do battle again. I had to find the strength to believe in myself when it seemed like no one else believed in me. When I hit a wall, I usually need to get more information to figure out what is going wrong. So, I did some research and found out that my initial vision for the book-where all the interview subjects got their own chapters-wasn't marketable to big publishers because that format does not sell tons of books. What I had to do was recognize, restructure and rewrite.

    I needed an agent. There are thousands of agents. Surely one of them was right for me. So, I started sending out query（询问）letters. Within a week, I had a dozen agents who wanted the book. I chose the one who I thought would believe in me and my dream. She did get me my choices of publishers.

    Hard won Wisdom wound up being a best-selling book. But, it almost never was.

     Aspirin has long been praised as a wonder drug. An aspirin a day keeps the doctor away. Many Americans have been taking one aspirin a day, believing it would protect them from a heart attack a stroke(中风), and even a cancer. But several recent studies have thrown this into question. Daily use of aspirin can have serious side effects(副作用).

    One study followed more than 19,000 healthy people aged 65 and older. They were required to take either 100 mg of aspirin (a little more than the 81 mg dose that most people take) or a placebo(无效对照剂) every day for about years, Not only did people in the aspirin group not lower their risk of heart disease, or disability but they were also more likely to suffer from bleeding into the brain or stomach. And they were more likely to die because of an increased risk of giving in to cancer, Similarly, an experiment of more than 12. 500 people aged 55 and older who have a cardiovascular (心血管的)risk found no benefit to taking aspirin daily. In study of more than 15,000 people with diabetes(糖尿病), a daily aspirin did prevent heart attacks and strokes, but it also caused serious bleeding.

    Although some earlier research has proved that aspirin can help people who have already had or are at high risk for heart attacks or strokes, the drug's value is not so clear for people, especially older people,

    The bottom line is this: Be smart and be safe. You should not take daily low-dose aspirin without talking to a doctor if you.

    ● Are over the age of 70

    ● Drink wine regularly

    ●Are on any simple medical operations

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