2019年托福阅读复习模拟练习题及答案解 析二托福阅读原文Petroleum, consisting of crude oil andnatural gas, seems to originate from organic matter in marine sediment.Microscopic organisms settle to the seafloor and accumulate in marine mud. Theorganic matter may partially decompose, using up the dissolved oxygen in thesediment. As soon as the oxygen is gone, decay stops and the remaining organicmatter is preserved.Continued sedimentation the process ofdeposits settling on the sea bottom buries the organic matter andsubjects itto higher temperatures and pressures, which convert the organic matter to oiland gas. As muddy sediments are pressed together, the gas and small droplets ofoil may be squeezed out of the mud and may move into sandy layers nearby. Overlong periods of time (millions of years), accumulations of gas and oil cancollect in the sandy layers. Both oil and gas are less dense than water, sothey generally tend to rise upward through water-saturated rock and sediment.Oil pools are valuable undergroundaccumulations of oil, and oil fields are regions underlain by one or more oilpools. When an oil pool or field has been discovered, wells are drilled intothe ground. Permanent towers, called derricks, used to be built to handle thelong sections of drilling pipe. Now portable drilling machines are set up andare then dismantled and removed. When the well reaches a pool, oil usuallyrises up the well because of its density difference with water beneath it orbecause of the pressure of expanding gas trapped above it. Although this riseof oil is almost always carefully controlled today, spouts of oil, or gushers,were common in the past. Gas pressuregradually dies out, and oil is pumpedfrom the well. Water or steam may be pumped down adjacent wells to help pushthe oil out. At a refinery, the crude oil from underground is separated intonatural gas, gasoline, kerosene, and various oils. Petrochemicals such as dyes,fertilizer, and plastic are also manufactured from the petroleum.As oil becomes increasingly difficult tofind, the search for it is extended into more-hostile environments. The developmentof the oil field on the North Slope of Alaska and the construction of theAlaska pipeline are examples of the great expense and difficulty involved innew oil discoveries. Offshore drilling platforms extend the search for oil tothe ocean1 s continental shelves - those gently sloping submarine regions at theedges of the continents. More than one- quarter of the worlds oil and almostone - fifth of the world 1 s natural gas come from offshore, even though offshoredrilling is six to seven times more expensive than drilling on land. Asignificant part of this oil and gas comes from under the North Sea betweenGreat Britain and Norway.Of course, there is far more oilunderground than can be recovered. It may be in a pool too small or too farfrom a potential market to justify the expense of drilling. Some oil lies underregions where drilling is forbidden, such as national parks or other publiclands. Even given the best extraction techniques, only about 30 to 40 percentof the oil in a given pool can be brought to the surface. The rest is far toodifficult to extract and has to remain underground.Moreover, getting petroleum out of theground and from under the sea and to the consumer can create environmentalproblems anywhere along the line. Pipelines carrying oil can be broken byfaults or landslides, causing serious oil spills. Spillage from hugeoil-carrying cargo ships, called tankers, involved in collisions or accidentalgroundings (such as the one off Alaska in 1989) can create oil slicks at sea.Offshore platforms may also lose oil, creating oil slicks that drift ashore andfoul the beaches, harming the environment. Sometimes, the ground at an oil fieldmay subside as oil is removed. The Wilmington field near Long Beach,California, has subsided nine meters in 50 years; protective barriers have hadto be built to prevent seawater from flooding the area. Finally, the refiningand burning of petroleum and its products can cause air pollution.Advancingtechnology and strict laws, however, are helping control some of these adverseenvironmental effects.托福阅读试题1. The word accumulate 55 in the passage(paragraph 1) is closest in meaning toA. grow upB. build upC. spread outD. break apart2. According to paragraph 1, which of thefollowing is true about petroleum formation?A. Microscopic organisms that live in mudproduce crude oil and natural gas.B. Large amounts of oxygen are needed forpetroleum formation to begin.C. Petroleum is produced when organicmaterial in sediments combines with decaying marine organisms.D. Petroleum formation appears to begin inmarine sediments where organic matter is present.sprimary purpose3. In paragraphs 1 and 2, the authoris toA. describe how petroleum is formedB. explain why petroleum formation is a slowprocessC. provide evidence that a marineenvironment is necessary for petroleum form