【文章內(nèi)容簡(jiǎn)介】 ing theories about the nature of the Earth39。s interior. Some geologiststhought that it contained a highly pressed ball of incandescent gas, while others Line suspected that it consisted of separate shells, each made of a different material. Today,(5) well over a century later, there is still little direct evidence of what lies beneath ourfeet. Most of our knowledge of the Earth39。s interior es not from mines or boreholes,but from the study of seismic wavespowerful pulses of energy released byearthquakes.The way that seismic waves travel shows that the Earth39。s interior is far from(10)uniform. The continents and the seabed are formed by the crusta thin sphere ofrelatively light, solid rock. Beneath the crust lies the mantle, a very different layer thatextends approximately halfway to the Earth39。s center. There the rock is the subject of a battle between increasing heat and growing pressure.In its high levels, the mantle is relatively cool。 at greater depths, high temperatures(15)make the rock behave more like a liquid than a solid. Deeper still, the pressure is evenmore intense, preventing the rock from melting in spite of a higher temperature.Beyond a depth of around 2,900 kilometers, a great change takes place and themantle gives way to the core. Some seismic waves cannot pass through the core andothers are bent by it. From this and other evidence, geologists conclude that the outer(20)core is probably liquid, with a solid center. It is almost certainly made of iron, mixedwith smaller amounts of other elements such as nickel.The conditions in the Earth39。s core make it a far more alien world than space. Its solid iron heart is subjected to unimaginable pressure and has a temperature of about176。F. Although scientists can speculate about its nature, neither humans normachines will ever be able to visit it. word conflicting in line 2 is closest in meaning to(A) controlling(B) outdated(C) opposing(D) important is today39。s richest source of informa tion about the Earth39。s interior for geologis ts?(A) Boreholes(B) Shells(C) Seismic waves(D) Mines word There in line 12 refers to the(A) mantle(B) crust(C) seabed(D) Earth39。s center of the following is a primary characteristic of the Earth39。s mantle?(A) Light, solid rock(B) Uniformity of position (C) Dramatically increasing pressure(D) Compressed, incandescent gas phrase gives way to in line 18 is closest in meaning to(A) runs along(B) rubs against(C) turns into(D) floats on word it in line 19 refers to (A) mantle(B) core(C) change(D) depth does the author state in line 22 that the Earth39。s core is more alien than space?(A) Government funds are not available to study the Earth39。s core.(B) Scientists aren39。t interested in the characteristics of the Earth39。s core.(C) It is impossible to go to the Earth39。s core to do research.(D) The Earth39。s core is made of elements that are word speculate in line 24 is closest in meaning to (A) report(B) learn(C) worry(D) hypothesizePassage 2The ocean bottom a region nearly times greater than the total land area of the Earth is a vast frontier that even today is largely unexplored and uncharted. Untilabout a century ago, the deepocean floor was pletely inaccessible, hidden beneath waters averaging over 3,600 meters deep. Totally without light and subjected to intense(5) pressures hundreds of times greater than at the Earth39。s surface, the deepocean bottomis a hostile environment to humans, in some ways as forbidding and remote as the void of outer space. Although researchers have taken samples of deepocean rocks and sediments for over a century, the first detailed global investigation of the ocean bottom did not (10)actually start until 1968, with the beginning of the National Science Foundation39。s Deep Sea Drilling Project (DSDP). Using techniques first developed for the offshore oil and gas industry. the DSDP39。s drill ship, the Glomar Challenger, was able to maintain a steady position on the ocean39。s surface and drill in very deep waters, extracting samplesof sediments and rock from the ocean floor. (15) The Glomar Challenger pleted 96 voyages in a 15year research program that ended in November 1983. During this time, the vessel logged 600,000 kilometers and took almost 20,000 core samples of seabed sediments and rocks at 624 drilling sitesaround the world. The Glomar Challenger39。s core samples have allowed geologists to reconstruct what the planet looked like hundreds of millions of years ago and to (20)calculate what it will probably look like millions of years in the future. Today, largely on the strength of evidence gathered during the Glomar Challenger39。s voyages, nearly all earth scientists agree on the theories of plate tectonics and continental drift that explain many of the geological processes that shape the Earth. The cores of sediment drilled by the Glomar Challenger have also yielded (25)information critical to understanding the world39。s past climates. Deepocean sediments provide a climatic record stretching back hundreds of millions of years, because theyare largely isolated from the mechanical erosion and the intense chemical and biologicalactivity that rapidly destroy much landbased evidence of past climates. This record has already provided insights into the patterns and causes of past climatic changeinformation that may be used to predict future climates. author mentions outer space in line 7 because(A) the Earth39。s climate millions of years ago was similar to conditions in outer space (B) it is similar to the ocean floor in being alien to the human environment (C) rock formations in outer space are similar to those found on the ocean floor(D) techniques used by scientists to explore outer space were similar to those used in ocean exploration Passage