单选题These apple trees,___________I planted three years ago, have not borne any fruit.

单选题I must tell you how ______ a letter from you.

单选题The Nobel Prizes are awards that are given each year for special things that people or groups ofpeople have achieved. They are awarded in six 21__________ : physics, chemistry, medicine, literature,pe

单选题Vicky has been sad recently, for her plan to go to college ______ at the last moment.

单选题 When global warming finally came, it stuck with a vengeance(报复). In some regions, temperatures rose several degrees in less than a century. Sea levels shot up nearly 400 feet, flooding coastal settlements and forcing people to migrate inland. Deserts spread throughout the world as vegetation shifted drastically in North America, Europe and Asia. After driving many of the animals around them to near extinction, people were forced to abandon their old way of life for a radically new survival strategy that resulted in widespread starvation and disease. The adaptation was farming: the global warming crisis that gave rise to it happened more than 10, 000 years ago. As environmentalists convene in Rio de Janeiro this week to ponder the global climate of the future, earth scientists are in the midst of a revolution in understanding how climate has changed in the past, and how those changes have transformed human existence. Researchers have begun to piece together an illuminating picture of the powerful geological and astronomical forces that have combined to change the planet's environment from hot to cold, wet to dry and back again over a time period stretching back hundreds of millions of years. Most important, scientists are beginning to realize that the climatic changes have had a major impact on the evolution of the human species. New research now suggests that climate shifts have played a key role in nearly every significant turning point in human evolution: from the dawn of primates (灵长目动物) some 65 million years ago to human ancestors rising up to walk on two legs, from the huge expansion of the human brain to the rise of agriculture. Indeed, the human history has not been merely touched by global climate change, some scientists argue, it has in some instances been driven by it. The new research has profound implications for the environmental summit in Rio. Among other things, the findings demonstrate that dramatic climate change is nothing new for planet Earth. The benign(宜人的) global environment that has existed over the past 10, 000 years—during which agriculture, writing, cities and most other features of civilization appeared—is a mere bright spot in a much larger pattern of widely varying climate over the ages. In fact, the pattern of climate change in the past reveals that Earth's climate will almost certainly go through dramatic changes in the future—even without the influence of human activity.

单选题The boss felt suspicious about the truth of the account, therefore, he determined to get down to having a good check.

单选题As the story proceeds, March begins to feel under the spell of______.

单选题When the ship was caught in a strong storm at the sea, the captain ______ a danger signal.

单选题Don't believe all of the stereotypes (模式化的形象) you may have heard about Americans. Even the ones that are true in general may not be true about specific individuals or a large part of the population. For example, although Americans tend to be louder than people from other cultures(especially at athletic events), many of the people you meet will be quiet and polite. Some people may be intolerant, but most will be pleasant and welcoming. Remember that American films and television exaggerate(夸张)in order to generate excitement, and so present a rather false picture of what life in the United States is really like. Therefore, tourists in the US are not always on their best behavior. Americans do tend to be more informal than people from other countries. It is common for Americans to wear casual clothing to school and to greet professors by first name. However, good manners and politeness are always appreciated. If you are polite, and dress a little more formally than your American friends, it will not be poorly thought of. However, some businesses require their employees to wear a uniform or a suit. It would be improper to wear a T-shirt and blue jeans to a job interview. Some of the more prestigious restaurants require a coat and tie. Americans tend to dress up for cultural events(the opera, theater and ballet)and to dress down for athletic events. Formal wear is required at weddings and funerals, or any other event with religious event. If you rely on the stereotypes, you will likely put yourself into an embarrassing situation

单选题Woman: Mr. Scott came back from L. A. very late yesterday. Man: So, even if he had been able to attend the party, he would have arrived late. Question: What do we learn about Mr. Scott?

单选题In English vocabulary, words of French ______ are not rare.

单选题As pointed out in Paragraph 3, the "evenly mixed" scenario

单选题The ______ garden looks very beautiful.

单选题Applicants should note that all positions are ______ to Australian citizenship requirements.

单选题When an invention is made, the inventor has three possible 61 of action open to him; he can give the invention to the world by publishing it, keep the idea 62 , or patent it. A 63 patent is the result of a bargain 64 between an inventor and the state, but the inventor gets a limited period of monopoly and publishes full details of his invention to the public after that period 65 . Only the most exceptional circumstances 66 the lifespan of a patent 67 to alter this normal process of events. The longest extension ever 68 was to Georges Valensi; his 1939 patent for color TV receiver circuit was extended until 1971 because for most of the patent's normal life there was no color TV to 69 and thus no hope for reward for the invention. Because a patent remains permanently 70 after it has terminated, the shelves of the library attached to the 71 office contain details of literally millions of ideas that are free for anyone to use and, if 72 than half a century, sometimes even re-patent. Indeed, patent experts often advise anyone 73 to avoid the high cost of conducting a search through 74 patents that the one sure way of violation of any other inventor's fight is to plagiarize a dead patent. Likewise, because publication of an idea in any other form 75 invalidates further patents on that idea. It is traditionally 76 to take ideas from other areas of print. Much modem technological advance is 77 on these presumptions of legal security. Anyone closely 78 in patents and inventions soon learns that most "new" ideas are, in fact, as old as the hills. It is their reduction to commercial practice, either through necessity or dedication, or through the availability of new technology, 79 makes news and money. The basic patent for the theory for magnetic recording dates back to 1886. Many of the original ideas behind television originate 80 the late 19th and early 20th century. Even the Volkswagen rear engine car was anticipated by a 1904 patent for a cart with the horse at the rear.

单选题This answer sounded ______.

单选题It has been raining for 3 ______ days, Monday, Tuesday and Wednesday. That's why the entire city has been flooded.

单选题 道家思想 道家思想(Taoism)是中国春秋时期(the Spring and Autumn Period)最重要的思想学派之一，创始人是老子。道家思想的核心是“道”(Tao)，老子用“道”来说明宇宙万物的产生和演变，认为人们在思想和行为上都要遵循“道”的规律，一切都要顺其自然。老子之后的另一位哲学家庄子继承和发展了道家思想。他强调自我提高，追求精神的自由。道家思想提倡追求自然、和谐的思想以及批判性思维的人文精神，是中国传统文化中宝贵而独特的精神财富。

单选题Please come back as soon as ______.