第三类

169.The commonest spaces are those among the particles—sand grainsand tiny pebbles—of loose,unconsolidated sand and gravel.

170.The water was always laden with pebbles, gravel, and sand, known asglacial outwash, that wasdeposited as the flow slowed down.

171.One, set forth by Aristotle in the fourth century B.C., sees humans asnaturally imitative—as takingpleasure in imitating persons, things, andactions and in seeing suchimitations.

172.The most widely accepted theory, championed by anthropologists in the late nineteenth and earlytwentieth centuries, envisions theater asemerging out of myth andritual.

173.In order for the structure to achieve the size and strength necessary tomeet its purpose, architectureemploys methods of support that, becausethey are based on physicallaws, have changed little since people firstdiscovered them-even whilebuilding materials have changed dramatically.

174.Estimates indicate that the aquifer contains enough water to fill Lake Huron,but unfortunately, under the semiarid climatic conditions thatpresently exist in the region,rates of addition to the aquifer are minimal,amounting to about half acentimeter a year.

175.Modern irrigation devices, each capable of spraying 4.5 million liters ofwater a day, have produced alandscape dominated by geometric patternsof circular green islands ofcrops.

176.This unprecedented development of a finite groundwater resource withan almost negligible naturalrecharge rate—that is, virtually no naturalwater source to replenish thewater supply—has caused water tables inthe region to fall drastically.

177.It is possible that tubes made from animal bones were used forspraying because hollow bones,some stained with pigment, have beenfound nearby.

178.A third opinion takes psychological motivation much further into therealm of tribal ceremonies andmystery: the belief that certain animalsassumed mythical significanceas ancient ancestors or protectors of agiven tribe or clan.

179.Advocates for this opinion point to reports from people who haveexperienced a trance state, ahighly suggestive state of low consciousnessbetween waking and sleeping.

180.The other species, the Columbian white-tailed deer, in earlier timeswas common in the open prairiecountry, it is now restricted to the low,marshy islands and floodplains along the lower Columbia River.

181.Hulmut Buechner(1953), in reviewing the nature of biotic changes inWashington through recordedtime, says that "since the early 1940s, thestate has had more deer thanat any other time in its history, the winterpopulation fluctuating aroundapproximately 320,000 deer (mule andblack-tailed deer), which willyield about 65,000 of either sex and any ageannually for an indefiniteperiod."

182.In addition to finding an increase of suitable browse, like huckleberryand vine maple, ArthurEinarsen, longtime game biologist in the Pacific Northwest, found qualityof browse in the open areas to be substantiallymore nutritive.

183.She rejected the technical virtuosity of movement in ballet, the mostprestigious form of theatricaldance at that time, perhaps because herformal dance training wasminimal.

184.Continued sedimentation—the process of deposits’ settling on the sea bottom—buries the organicmatter and subjects it to higher temperaturesand pressures, which convertthe organic matter to oil and gas.

185.Spillage from huge oil-carrying cargo ships, called tankers, involved incollisions or accidentalgroundings (such as the one off Alaskain 1989)can create oil slicks at sea.

186.This “atmospheric engine,” invented by Thomas Savery and vastlyimproved by his partner,Thomas Newcomen, embodied revolutionaryprinciples, but it was so slowand wasteful of fuel that it could not beemployed outside the coalmines for which it had been designed.

187.In 1815 he published the first modern geological map “A Map of theStrata of England and Wales with aPart of Scotland”, a map someticulously researched that it can stillbe used today.

188.Even without the problem of regional differences, rocks present adifficulty as unique timemarkers: Quartz is quartz—a silicon ionsurrounded by four oxygenion—there’s no difference at all betweentwo-million-year-oldPleistocene quartz and Cambrian quartz created over500 million years ago．

189.Limestone may be found in the Cambrian or 300 million years later inthe Jurassic strata but atrilobite-the ubiquitous marine arthropod that hadits birth in the Cambrian-willnever be found in Jurassic strata, nor adinosaur in the Cambrian.

190.While rock between two consistent strata might in one place be shaleand in another sandstone, thefossils in that shale or sandstone werealways the same.

191.Nor does the hypothesis that infantile amnesia reflects repression- orholding back- of sexuallycharged episodes explain the phenomenon．

192.Thus, all three explanations-- physiological maturation, hearing andproducing stories about pastevents，and improved encoding of keyaspects of events--seem likelyto be involved in overcoming infantileamnesia．

193.Aeroponics, a technique in which plants are suspended and the rootsmisted with a nutrientsolution, is another method for growing plantswithout soil.

194.Saline soils, which have high concentrations of sodium chloride andother salts, limit plantgrowth, and research continues to focus ondeveloping salt-tolerantvarieties of agricultural crops.

195.After several years of cultivation and harvest, the site would berestored at a cost much lowerthan the price of excavation and reburial, thestandard practice forremediation of contaminated soils.

196.The culture of that time, based on archaeology and linguisticreconstruction, is assumed tohave had a broad inventory of cultivatedplants including taro, yarns,banana, sugarcane, breadfruit, coconut, sago,and rice.

197.As a result of crustal adjustments and faulting, the Strait of Gibraltar, where the Mediterranean nowconnects to the Atlantic, opened, and watercascaded spectacularly backinto the Mediterranean.

198.These peoples settled at first in scattered hunting-and-gathering bands,although in some places nearlakes and rivers, people who fished, with amore secure food supply, livedin larger population concentrations.

199.Their migration may have been set in motion by an increase inpopulation caused by amovement of people’s fleeing the desiccation, ordrying up, of the Sahara.

200.It seems likely that Teotihuacán’s natural resources―along with thecity elite’s ability torecognize their potential―gave the city a competitiveedge over its neighbors.

201.Off and on throughout the Cretaceous (the last period of the Mesozoicera, during which dinosaursflourished), large shallow seas coveredextensive areas of thecontinents.

202.Data from diverse sources, including geochemical evidence preservedin seafloor sediments,indicate that the Late Cretaceous climate wasmilder than today’s.

203.It’s hard to understand why they would not be affected, whereasdinosaurs were left toocrippled to cope, especially if, as some scientistsbelieve, dinosaurs werewarm-blooded.

204.In view of these facts, scientists hypothesized that a single largeasteroid, about 10 to 15kilometers across, collided with Earth, and theresulting fallout created theboundary clay.

205.These flow features are extensive systems ―sometimes hundreds ofkilometers in total length ―ofinterconnecting, twisting channels that seemto merge into larger, widerchannels.

206.A 2003 Mars Global Surveyor image shows what mission specialiststhink may be a delta―afan-shaped network of channels and sedimentswhere a river once flowed intoa larger body of water, in this case a lakefilling a crater in thesouthern highlands.

207.The Hellas Basin, which measures some 3,000kilometers across andhas a floor that lies nearly 9 kilometersbelow the basin’s rim, is anothercandidate for an ancientMartian sea.

208.Furthermore, Mars Global Surveyor data released in 2003 seem toindicate that the Martiansurface contains too few carbonate rocklayers ―layers containingcompounds of carbon and oxygen ―that shouldhave been formed in abundancein an ancient ocean.

209.Aside from some small-scale gullies (channels) found since 2000,which are inconclusive,astronomers have no direct evidence for liquidwater anywhere on the surfaceof Mars today, and the amount of watervapor in the Martianatmosphere is tiny.

210.It had been assumed that the ice extended westward from theAlaskan/Canadian mountains tothe very edge of the continental shelf, theflat, submerged part of thecontinent that extend into the ocean.

211.One study suggests that except for a 250-mile coastal area betweensouthwestern British Columbia and Washington State, the NorthwestCoast of North America waslargely free of ice by approximately 16,000years ago.

212.Teachers, it is thought, benefit from the practice of reflection, theconscious act of thinkingdeeply about and carefully examining theinteractions and events withintheir own classrooms.

213.Wildman and Nileswere particularly interested in investigating theconditions under whichreflection might flourish-a subject on which there islittle guidance in theliterature.

214.The teachers were taken through a program of talking about teachingevents, moving on toreflecting about specific issues in a supported, andlater an independent, manner.

215.Further observation revealed the tendency of teachers to evaluateevents rather than review thecontributory factors in a considered mannerby, in effect, standingoutside the situation.

216.There appear to be many unexplored matters about the motivation toreflect-for example, the valueof externally motivated reflection as opposedto that of teachers who mightreflect by habit.

217.It is significant that the earliest living things that built communities onthese islands are examples ofsymbiosis, a phenomenon that dependsupon the close cooperation oftwo or more forms of life and a principle thatis very important in islandcommunities.

218.Now, other forms of life could take hold: ferns and mosses (two of themost ancient types of landplants) that flourish even in rock crevices.

219.These plants propagate by producing spores-tiny fertilized cells thatcontain all the instructionsfor making a new plant-but the spores areunprotected by any outercoating and carry no supply of nutrient.

220.However, unlike the cases of sea otters and pinnipeds (seals, sea lions,and walruses, whose limbs arefunctional both on land and at sea), it is noteasy to envision what thefirst whales looked like.

221.Many incomplete skeletons were found but they included, for the firsttime in an archaeocyte, acomplete hind leg that features a foot with threetiny toes.

222.The deserts, which already occupy approximately a fourth of theEarth's land surface, have inrecent decades been increasing at analarming pace.

223.For the price of 25 cents (or 5 cents per machine), customers movedfrom machine to machine towatch five different films (or, in the case offamous prizefights, successiverounds of a single fight).

224. Edison was more interested in the sale of Kinetoscopes (forroughly$1,000 apiece) to these parlors than in the films that wouldbe run in them(which cost approximately $10 to $15 each).

225.The Democrats tended to view society as a continuing conflict between "thepeople”-farmers, planters, and workers-and a set of greedyaristocrats.

226.All groups, including the Fore, who had almost no contact with Westernculture, agreed on theportrayed emotions.

227.On the other hand, the repression, as far as possible, of all outwardsigns softens our emotions.

228.Causing participants in experiments to smile, for example, leads themto report more positivefeelings and to rate cartoons (humorous drawingsof people or situations) asbeing more humorous.

229.Ekman has found that the so-called Duchenne smile, which ischaracterized by ''crow’sfeet" wrinkles around the eyes and a subtle dropin the eye cover fold so thatthe skin above the eye moves down slightlytoward the eyeball, can leadto pleasant feelings.

230.Most people consider the landscape to be unchanging, but Earth is adynamic body, and its surfaceis continually altering-slowly on the humantime scale, but relativelyrapidly when compared to the great age of Earth(about 4,500 billion years).

231.Many of her dances represented elements or natural objects—Fire, theLily, the Butterfly, and soon—and thus accorded well with the fashionableArt Nouveau style, whichemphasized nature imagery and fluid, sinuouslines.

232.Her dancing also attracted the attention of French poets and paintersof the period, for it appealedto their liking for mystery, their belief in art forart’s sake, anineteenth-century idea that art is valuable in itself rather thanbecause it may have some moralor educational benefit, and their efforts tosynthesize form and content.

233.At the Paris Exposition in 1900, she had her own theater, where, inaddition to her own dances,she presented pantomimes by the Japaneseactress Sada Yocco.

234.They are formed by glaciers—large rivers of ice that begin inland in thesnows of Greenland,Antarctica, and Alaska—andmove slowly toward thesea.

235.Recent expeditions have taken ice samples from green icebergs andice cores—vertical,cylindrical ice samples reaching down to greatdepths—from the glacial iceshelves along the Antarctic continent.

236.The ice shelf cores, with a total length of 215 meters (705 feet), werelong enough to penetratethrough glacial ice—which is formed from thecompaction of snow andcontains air bubbles—and to continue into theclear, bubble-free ice formedfrom seawater that freezes onto the bottom ofthe glacial ice.