【正文】 uctures present in air closely resemble the microorganisms seen in putrefying materials .He did (10) this by passing air through guncotton filters, the fibers of which stop solid particles. Afterthe guncotton was dissolved in a mixture of alcohol and ether, the particles that it had trapped fell to the bottom of the liquid and were examined on a microscope slide .Pasteurfound that in ordinary air these exists a variety of solid structures ranging in size from mm to more than mm .Many of these bodies resembled the reproductive (15)structures of mon molds, singlecelled animals, and various other microbial cells .As many as 20 to 30 of them were found in fifteen liters of ordinary air ,and they couldnot be distinguished from the organisms found in much larger numbers in putrefying materials .Pasteur concluded that the organisms found in putrefying materials originated from the organized bodies present in the air .He postulated that these bodies are constantly(20)being deposited on all objects.Pasteur showed that if a nutrient solution was sealed in a glass flask and heated to boiling to destroy all the living organisms contaminating it, it never putrefied .The proponents of spontaneous generation declared that fresh air was necessary for spontaneous generation and that the air inside the sealed flask was affected in some way (25)by heating so that it would no longer support spontaneous generation. Pasteur constructed a swannecked flask in which putrefying materials could he heated to boiling, but aircould reenter. The bends in the neck prevented microorganisms from getting in the flask.. Material sterilized in such a flask did not putrefy.1,What does the passage mainly discuss?(a)Pasteur’s influence on the development of the microscope.(b)The origin of the theory of spontaneous generation .(c)The effects of pasteurization on food.(d)Pasteur’s argument against the theory of spontaneous generation .2,The phrase “teeming with ”in line 2 is closest in meaning to(a)full of(b)developing into(c)resistant to(d)hurt by 3,Which of the following questions did the theory of spontaneous generation attempt to answer?(a)What is the origin of the living organisms are seen on some food?(b)How many types of organisms can be found on food?(c)What is the most effective way to prepare living organisms for microscopic examination?(d)How long can food stand before it putrefies?4,The word “resemble” in line 9 is closest in meaning to(a)benefit from(b)appear similar to(c)join together with(d)grow from5,The purpose of the “guncotton” mentioned in paragraph 2 was to(a)trap particles for analysis(b)slow the process of putrefaction(c)increase the airflow to the microscopic slide(d)aid the mixing of alcohol and ether6,The author mention “”in line 14 in describing the (a)thickness of a layer of organisms that was deposited on an object(b)diameter of the fibers that were in the guncotton filters(c)thickness of the microscope slides that were used(d)size of the particles that that were collected word “postulated”in line 19 is closest in meaning to(a)analyzed(b)doubted(c)persuaded(d)suggested objects that Pasteut removed from the air in his experiment were remarkable because they were(a)primarily singlecelled organisms(b)no different from objects found in putrefying materials(c)fairly rare(d)able to live in a mixture of alcohol and ether word “it” in line 22 refers to (a)a nutrient solution(b)a glass flask(c)boiling(d)spontaneous generation to paragraph 3,proponents of spontaneous generation believed that which of the following was important for the process to succeed ?(a)A sealed container(b)Fresh air(c)Heat(d)The presence of nutrients can be inferred from paragraph 3 that Pasteur employed a swamnecked flask to(a)store sterilized liquids for use in future experiments(b)prevent heat from building up in a solution (c)disprove a criticism of his conclusions(d)estimate the number of organisms in a liter of airQuestions 1220In the early decades of the United States ,the agrarian movement promoted the farmeras society’s hero. In the minds of agrarian thinkers and writers ,the farmer was a person on whose wellbeing the health of the new country depended .The period between the Revolution, which ended in 1783,and the Civil War ,which ended in 1865 ,was the age of (5 )the farmer in the United States .Agrarian philosophers ,represented most eloquently byThomas Jefferson, celebrated farmers extravagantly for their supposed centrality in a good society, their political virtue ,and their Superior morality .And virtually all policy makers, whether they subscribed to the tenets of the philosophy held by Jefferson or not, recognized agriculture as the key ponent of the American economy .Consequently ,government at (10) all levels worked to encourage farmers as a social group and agriculture as economic enterprise.Both the national and state governments developed transportation infrastructure,building canals, roads, bridges, and railroads ,deepening harbors ,and removing obstructions from navigable streams .The national government imported plant and animal varieties and(15) launched exploring expeditions into prospective farmlands in the West .In addition ,government trade policies facilitated the exporting of agricultural products.For their part ,farmers seemed to meet the social expectations agrarian philosophershad for them ,as their broader horizons and greater selfrespect, both products of the Revolution ,were reflected to some degree in their behavior .Farmers seemed to bee (20) more scientific ,joining agricultural societies and reading the farm newspapers that sprang up throughout the country .They began using improved implements, tried new crops and pure animal breeds , and became more receptive to modern theories of