单选题 At the present time, 98 percent of the world energy consumption comes from stored sources, such as fossil fuels or nuclear fuel. Only hydroelectric and wood energy represent completely renewable sources on ordinary time scales. Discovery of large additional fossil fuel reserves, solution of the nuclear safety and waste disposal problems, or the development of controlled thermonuclear fusion will provide only a short-term solution to the world's energy crisis. Within about 100 years, the thermal pollution resulting from our increased energy consumption will make solar energy a necessity at any cost. Man's energy consumption is currently about one part in ten thousand that of the energy we receive from the sun. However, it is growing at a 5 percent rate, of which about 2 percent represents a population growth and 3 percent a per capita energy increase. If this growth continues, within 100 years our energy consumption will be about 1 percent of the absorbed solar energy, enough to increase the average temperature of the earth by about one degree centigrade if stored energy continues to be our predominant source. This will be the point at which there will be significant effects in our climate, including the melting of the polar ice caps, a phenomenon which will raise the level of the oceans and flood parts of our major cities. There is positive feedback associated with this process, since the polar ice cap contributes to the partial reflectivity of the energy arriving from the sun: As the ice caps begin to melt, the reflectivity will decrease, thus heating the earth still further. It is often stated that the growth rate will decline or that energy conservation measures will preclude any long-range problem. Instead, this only postpones the problem by a few years. Conservation by a factor of two together with a maintenance of the 5 percent growth rate the problem by only 14 years. Reduction of the growth rate to 4 percent postpones the problem by only 25 years; in addition, the inequities in standards of living throughout the world will provide pressure toward an increase in growth rate, particularly if cheap energy is available. The problem of a changing climate will not be evident until perhaps ten years before it becomes critical due to the nature of an exponential growth rate together with the normal annual weather variations. This may be too short a period to circumvent the problem by converting to other energy sources, so advance planning is a necessity. The only practical means of avoiding the problem of thermal pollution appears to be the use of solar energy. (Schemes to "air-condition" the earth do not appear to be feasible before the twenty-second century. ) Using the solar energy before it is dissipated to heat does not increase the earth's energy balance. The cost of solar energy is extremely favorable now, particularly when compared to the cost of relocating many of our major cities.

单选题 America's recent history has been a persistent tilt to the West—of people, ideas, commerce and even political power. California and Texas are the twin poles of the West, but very different ones. For most of the 20th century the home of Silicon Valley and Hollywood has been the brainier and trendier of the two. Texas has trailed behind: its stereotype has been a conservative Christian in cowboy boots. But twins can change places. Is that happening now? It is easy to find evidence that California is in a panic. At the start of this month the once golden state started paying creditors in IOUs (欠条). The gap between projected outgoings and income for the current fiscal (财政的) year has leapt to a horrible $ 26 billion. With no sign of a new budget to close this gulf, one credit agency has already downgraded California's debt. As budgets are cut, universities will let in fewer students, prisoners will be released early and schemes to protect the vulnerable will be rolled back. By contrast, Texas has coped well with the recession, with an unemployment rate two points below the national average and one of the lowest rates of housing repossession. In part this is because Texan banks, hard hit in the last property bust, did not overexpand this time. Texas also clearly offers a different model, based on small government. It has no state capital-gains or income tax, and a business-friendly and immigrant-tolerant attitude. It is home to more Fortune 500 companies than any other state. Despite all this, it still seems too early to hand over America's future to Texas. To begin with, that lean Texan model has its own problems. It has not invested enough in education, and many experts rightly worry about a 'lost generation' of mostly Hispanic Texans with insufficient skills for the demands of the knowledge economy. Second, it has never paid to bet against a state with as many inventive people as California. Even if Hollywood has gone into depression, it still boasts an unequalled array of sunrise industries and the most brisk venture-capital industry on the planet. The state also has an awesome ability to reinvent itself—as it did when its defence industry collapsed at the end of the cold war. The truth is that both states could learn from each other. Texas still lacks California's great universities and lags in terms of culture. California could adopt not just Texas's leaner state, but also its more bipartisan (两党的) approach to politics. There is no perfect model of government; it is America's genius to have 50 public-policy laboratories competing to find out what works best.

单选题She ______ herself bitterly for her behavior that evening. A. blamed B. accused C. reproached D. scolded

单选题It is high time we ______. A. leave B. left C. will leave D. have left

单选题It was a cold spring morning in London. People walking in the street were wearing heavy clothes. The weather had been very bad for the past week, and now many people were ill. Today there were quite a few people in the doctor's waiting room. There were still a few minutes before the doctor started seeing the patients (患者). A man of about seventy years old was at the front of the queue (排队). He did not live in this city. He came from a farm north of London, he was here to visit his daughter who was a secretary in a big company. He wanted to see the doctor because of his back problem. Soon an Indian (印度人) came into the waiting room, and walked straight to the doctor's door. When he saw this, the old man stood up and took hold of his arm. He said slowly, "We were all here before you. You must wait for your mm. Do... you... understand?" The Indian answered, "No, Sir. You don't understand! You're all after me! I am the doctor!/

单选题All of the plants now raised on farms have been developed from plants ______ in the wild. A. once they grew B. that once grew C. they grew once D. once grew

单选题Yesterday you were acclaimed; today you are ______.Isn't life full of ups and downs? A. lauded B. censured C. savored D. appraised

单选题More than thirty people are______in this event.

单选题Owing to ______ competition among the airlines, travel expenses have been reduced considerably.

单选题What's the tone of the author towards "Terminator''?

单选题Each has an apple, ______?

单选题 自驾游(self-driving tour)属于自助旅游的一种类型，是近年来我国新兴的旅游方式，以自由、灵活、富有个性化等突出特点被旅游者接受和喜爱。自驾游在选择目的地、参与旅程设计和体验自由等方面，给旅游者提供了极大的灵活性，与传统的参团旅游(group tour)相比具有自身的特点和魅力。随着自驾旅游者的增多，自驾游市场已经成形，越来越多的旅行社、汽车俱乐部、汽车租赁公司(car rental companies)看好这一市场，并涉足这一市场的开发。

单选题There isn't sound proof to support his biological theory.

单选题The colors of that coat and hat don't ______ .

单选题NASA is releasing several images taken by the Hubble Space Telescope, which is the closest yet look at the red planet. Altogether there are four images, which show the entire planet. Each view shows the planet as it completes one quarter of its daily rotation. In these views the north polar cap is turned toward the Earth and is clearly visible at the top of each picture. The images were taken in the middle of the Martian northern summer, when the polar cap was at its smallest size. During this season the sun shines continuously on the polar cap. Previous spacecraft observations have shown that this summertime polar cap is composed of water ice, just like Earth's polar caps. The Hubble Telescope pictures reveal that great changes have occurred on the surface of Mars in the past 20 years. The Martian surface is ever changing. Some regions that were dark 20 years ago are now bright red; some areas that were bright red are now dark. Winds move sand and dust from region to region, often in huge dust storms. Over long timescales many of the larger bright and dark markings remain stable, but smaller details come and go as they are covered and then uncovered by sand and dust.

单选题ADULTERATE: PURE

单选题I cannot tell the______difference between the twins.

单选题The fact that something is cheap doesn’t _________ mean it is of low quality.

单选题A good plan when fighting against an enemy tank is to ______.

单选题The results obtained agreed approximately with ______ expected. A. that B. one C. those D. ones