Even when you're extremely busy, you aren't using your time with 100% efficiency. There are gaps in everyone's schedule where they aren't doing anything important. Even if your schedule hasno gaps, there is probably lots of time where you aren't working as fast or as effectively as you possibly could.

    Why aren't you completely efficient? It's because time isn't thelimiting factor. If it were the limiting factor, people could work non-stop without breaks or any unproductive distractions. Instead, people, even those who are highly productive, need to take breaks, occasionally procrastinate(拖延) and slow downon tasks throughout the day.

    The real and most important limiting factor for productivity is your energy levels to pay attention. Energy levels limit your productivity because when you're tired, you can have ample time and still not get everything done. Your attention ability is also limited, because even if there are amillion things that need to be done, you can only focus on one or two at a time.

    You might not be able to insert another 4-5 hours into your schedule without making some sacrifices. But even extremely busy people can addan hour or two into their schedule without can celling anything. The reason it's hard to “find time” isn't a lack of time. It's because you don't have enough energy left to focus on something else that needs to fit into your day.

    I first suspected time wasn't the real problem during an extremely busy period in my life over a year ago. I was insanely busy, but at that time I still exercised regularly. I had daily-to-do lists with over twenty items, and I still found time to exercise. However, after a few weeks off, due to illness, stopped exercising. I was not busy by any standards, in fact, my schedule was incredibly light. Despite this free time, I found it hard to find time to exercise. It seemed to get pushed later and later into my schedule until it was gone. How can I explain this odd experience? I believe you haveknown it.

    In 1905, as part of his Special Theory of Relativity, Albert Einstein published the point that a large amount of energy could be released from a small amount of matter. This was expressed by equation E = me 2(energy = mass times the speed of light squared). But bombs were not what Einstein had in mind when he published this equation.

    In 1929, he publicly declared that if a war broke out he would “refused to do war service, direct or indirect…” His position would change in 1933, as the result of Adolf Hitler's coming into power in Germany.

    Einstein's greatest role in the invention of the atomic bomb was signing a letter to President Franklin Roosevelt urging that the bomb be built because some physicists feared that Germany might be working on an atomic bomb. Among those concerned were physicists Leo Szilard and Eugene Wigner. But Szilard and Wigner had no influence with those in power. So in July 1939 they explained the problem to someone who did: Albert Einstein. After talking with Einstein, in August 1939 Szilard wrote a letter to President Roosevelt with Einstein's signature on it, which was delivered to Roosevelt in October 1939.

    Germany has invaded Poland the previous month; the time was ripe for action. That October research of a-bomb began but proceeded slowly because the invention of the atomic bomb seemed distant and unlikely. In April 1940 an Einstein letter, ghost-written by Szilard, pressed the researchers on the need for “greater speed”.

    As the realization of nuclear weapons grew near, Einstein looked beyond the current war to future problems that such weapons could bring. He wrote to his friend about his fear about the future use of the a-bomb.

    The atomic bombings of Japan occurred three months after Germany gave in.

In November 1954, five months before his death, Einstein summarized his feelings about his role in the creation of the atomic bomb: “I made one great mistake in my life… when I signed a letter to President Roosevelt recommending that atom bombs be made; but there was some justification—- the danger that the Germans would make them”.

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。

    Art museums are places where people can learn about various cultures. The increasingly popular “design museums” that are opening today, however, perform quite a different role. Unlike most art museums, the design museums show objects that are easily found by the general public. These museums sometimes even place things like fridges and washing machines in the centre of the hall.

    People have argued that design museums are often made use of as advertisements for new industrial technology. But their role is not simply a matter of sales—it's the honouring of excellently invented products. The difference between the window of a department store and the showcase in a design museum is that the first tries to sell you something, while the second tells you the success of a sale.

    One advantage of design museums is that they are places where people feel familiar with the exhibits. Unlike the average art museum visitors, design museum visitors seldom feel frightened or puzzled. This is partly because design museums clearly show how and why mass－produced products work and look as they do, and how design has improved the quality of our lives. Art museum exhibits, on the other hand, would most probably fill visitors with a feeling that there is something beyond their understanding.

    In recent years, several new design museums have opened their doors. Each of these museums has tried to satisfy the public's growing interest in the field with new ideas. London's Design Museum, for example, shows a collection of mass－produced objects from Zippo lighters to electric typewriters to a group of Italian fish－tins. The choices open to design museums seem far less strict than those to art museums, and visitors may also sense the humorous part of our society while walking around the exhibits.

    Blue Planet II's latest episode focuses on how plastic is having a disastrous effect on the ocean and slowly poisoning our sea creatures. Researchers recently also found that sea creatures living in the deepest place on Earth, the Mariana Trench, have plastic in their stomachs. Indeed, the oceans are drowning in plastic.

    Though it seems now that the world couldn't possibly function without plastics, consumer plastics are a remarkably recent invention. The first plastic bags were introduced in the 1950s; the same decade that plastic packaging began gaining in popularity in the United States. This growth has happened so fast that science is still catching up with the change. Plastics pollution research, for instance, is still a very early science.

    We put all these plastics into the environment and we still don't really know what the outcomes are going to be. What we do know, though, is disturbing. Ocean plastic is estimated to kill millions of marine animals every year. Nearly 700 species, including endangered ones, are known to have been affected by it. One in three leatherback turtles, which often mistake plastic bags for jellyfish, have been found with plastic in their bellies. Ninety percent of seabirds are now eating plastics on a regular basis. By 2050, that figure is expected to rise to 100 percent.

    And it's not just wildlife that is threatened by the plastics in our seas. Humans are consuming plastics through the seafood we eat. I could understand why some people see ocean plastic as a disaster, worth mentioning to the same degree as climate change. But ocean plastic is not as complicated as climate change. There are no ocean trash deniers (否认者), at least so far. To do something about it, we don't have to remake our planet energy system.

This is not a problem where we don't know what the solution is. We know how to pick up garbage. Anyone can do it. We know how to dispose (处理) of it. We know how to recycle. We can all start by thinking twice before we use single-use plastic products. Things that may seem ordinary, like using a reusable bottle or a reusable bag—when taken collectively, these choices really do make a difference.

As I have perfect pitch(绝对音感) and started playing piano at 3 years old, it's much natural for me to join the school's choir when I got to college in the US.

At first, everything went pretty 1 . I passed the audition(试音), and was even invited to join the more selective Chamber Singers. However, I soon became 2 after several rehearsals(排练). From jokes to music theory, I simply couldn't understand what they were talking about! And when I 3 others' pitch mistakes, they seemed unwilling to accept. I remained silent even when I knew the pitches were 4 .

It was our New Year Concert last year that 5 me out of deep waters. When we were singing the words of a song: "To live is to give", I thought "how could I be 6 just being a silent Asian?" Soon after the 7 , I started my plan. In my second term, I 8 to join all the conversations and started to help fellow singers with my abilities 9 identifying pitch. I was overwhelmed by the content of helping people, and was thrilled 10 more choir members came to me for casual talks.

From March to May, I was 11 soloist(独唱者) for four different songs, an unusual 12 for a first-year student. Among them, my favorite piece was a Spanish folk song that we 13 during the choir's spring tour to Madrid. A Chinese student singing a Spanish song in an American choir—how proud I was to 14 as an ambassador of cross-cultural communication! When the audience applauded us, I came to see a better world with understanding, 15 and love.

"Having the world at our fingertips" is a metaphor often used when we put our hands on information technology, like smartphones and computers. This is a good metaphor. But what is much better is how we use our hands to make things done.

Put one hand flat on a surface, palm down, and you might be able to make out the outline of 14 short bones in your thumb and fingers, in addition to 5 longer ones in your palm that are jointed to your wrist. These bones give each hand its rigid, knuckled structure. Together they're critical components of the anatomical （解剖的） architecture that allows your hand to move. At each of your fingertips there's an ever-growing, translucent plate of fibrous protein, otherwise known as a nail. Although they're nice for decoration, your nails protect and enhance your sensitivity to touch, too.

Imagine squeezing a piece of paper between your thumb and index finger, for example. We use this type of forceful pad-to-pad precision grasping without thinking about it, and literally in no time. Yet it was a breakthrough in human evolution. Other primates （灵长目动物） exhibit some kinds of precision grasps in the handling and use of objects, but not with the kind of efficiency that our hand does.

With a unique combination of traits, the human hand shaped history. No question, stone tools couldn't have become a keystone of human technology without hands that could do the job, along with a nervous （神经的） system that could regulate and coordinate the necessary signals. Even for those who have never attempted to make a spear tip or arrowhead from a rock, it's obvious that it would require strong grasps, constant rotation and repositioning, careful strikes with another hard object. And even for those who have done so, it can be a bloody business.

Of course, the most common object that people touch nowadays is a screen. And the tap-tap-tap movement of our fingers is a unique human ability, as no other primate can move their fingers as rapidly and independently as we do. Here again, we can thank the extraordinary human brain given that normal finger tapping requires the functional integrity of different parts of our central nervous system.