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GRE閱讀高頻機(jī)經(jīng)原文：Snowshoe hare population　

Snowshoe hare population

The snowshoe hare is one of the northern mammals that go through periodic cycles of changes in their populations. Over a period of years, their population will increase in numbers and then suddenly crash to very low numbers, only to rise again. Snowshoe hare tend to cycle about once every ten years. The snowshoe hare cycle is one of the best known and fur trappers and traders working in northern Canada first described it. In 1865, traders with the Hudson's Bay Company were flooded by hare pelts brought in by trappers. But, by 1870, only a few hare pelts trickled in. This pattern of high and low abundance of hare pelts repeated itself over and over, roughly every ten years.

Snowshoe hares are a dominant herbivore in northern forest ecosystems. In Alaska and western Canada, their populations cycle over 8 to 11 years. The difference in densities and abundance during the cycle are extreme. Densities as high as 4,000 hares per square kilometer (or 10,000 hares per square mile) have been estimated at the peak (or high point) of the cycle. These populations can "crash" to densities of less than one hare per square kilometer (or 2.6 hares per square mile) within a period of one year. The populations slowly increase to peak densities over the next 6 to 13 years. The densities during peak years, however, are not always the same.

Just what is it that drives the snowshoe hare cycle? This question has puzzled people living in northern areas and scientists for many years. On a broad scale, it may be the 22- year sunspot cycle and its effects on boreal forest weather patterns or forest fires. On a smaller scale, the cycles may be affected by over browsing the food supply, predators, shock disease due to stress, parasites, or a combination of these. The primary theory pertaining to the snowshoe hare population cycle describes the mechanics as a combination of predators and browse (food) availability. During the peak of their cycle, hares eat a large proportion of the shrubs available in their area. They can also kill many of the shrubs in their area by chewing through the outer layer of bark. Over-browsing of shrubs results in a food-shortage that causes malnourishment, starvation, and reduced reproduction. This leads to the start of the population crash or decline. Also, as food supplies decrease, the health of hares declines and makes many individuals more vulnerable to predators and disease. In the western Yukon, scientists believe that the hare cycle is caused by changes in food supply and predation. The declines and increases in the population of hares were influenced by the reproductive rates of adult hares and the survival rates of all ages of hares.

GRE閱讀詞匯精選之ine結(jié)尾的動(dòng)物

aquiline　adj.鷹的，似鷹的.

asinine　adj.愚笨的

bovine　adj.(似)牛的，遲鈍的

canine　adj.犬的，似犬的

elephantine　adj.笨拙的,巨大的

equine　adj.馬的,似馬的

feline　adj.貓科的

leonine　adj.獅子的

porcine　adj.豬的,似豬的

porcupine　　　n.豪豬,箭豬

serpentine　adj.似蛇般繞曲的，蜿蜒的

ursine　adj.熊的，像熊的

vulpine　adj.狐貍的，狡猾的

lupine　adj　狼的，殘忍的，貪吃的

colubrine　adj　無毒蛇的，似蛇的

cervine　adj　鹿的，鹿一樣的

GRE詞匯精選之格言

adage　n.格言，古訓(xùn)

aphorism　n.格言

dictum　n.格言、聲明

gnome　n.地下寶藏的守護(hù)神，地精，格言

gnomic　adj.格言的，精辟的

maxim　n.格言，普遍真理

motto　n.座右銘，箴言

precept　n.箴言,格言

epigram　n.警句，諷刺短詩

epigrammatic　adj.警句的

phrase　n.警句，· 樂句，· 短語

還有saying,proverb

GRE閱讀精選詞匯之幾種笑

chortle　v.n.開心地笑

chuckle　v.輕聲地笑

guffaw　n.v.哄笑，大笑

simper　v.傻笑、假笑

smirk　v.假笑，得意地笑

snigger　v.n.暗笑，竊笑　(=snicker)

giggle　v.(女孩)咯咯的笑

titter　v.嗤嗤的笑,偷笑

grin　v.露齒而笑

GRE閱讀精選詞匯之大敗,失敗,戰(zhàn)勝

fiasco　n.大失敗，慘敗

massacre　n.大屠殺，大敗

rout　n.大敗，潰敗

checkmate　n.(象棋中)被將死時(shí)王的位置，完全失敗

lurch　n　挫敗，大敗

washout　n　沖刷，失敗

founder　v.(船)沉沒，(計(jì)劃)失敗

fizzle　n　咝咝聲，失敗

flummox　v.使混亂，背誦出錯(cuò)　n.失敗

flop　n.　失敗　v　笨重的摔

balk　n.障礙,錯(cuò)誤,失敗

balk　n.障礙,錯(cuò)誤,失敗　　vt.阻止,突然停止,退縮

bungle　v\n拙劣地工作,粗制濫造,失敗

confound　v　使混淆,使狼狽,挫敗

frustrate　v.挫敗，使沮喪

pulverize　v.壓成細(xì)粉,徹底擊敗

scalp　n.頭皮，· 戰(zhàn)利品v.擊敗

paste　v　狠狠地打，· 擊敗

abortive　adj.無結(jié)果的，· 失敗的

crestfallen　adj.挫敗的，· 失望的

internecine　adj.內(nèi)訌的,兩敗俱傷的

circumvent　v.用計(jì)謀戰(zhàn)勝，· 規(guī)避

landslide　n.山崩，· 壓倒性勝利

outfox　v.以機(jī)智勝過

outwit　v.以機(jī)智勝過

prevail　v.戰(zhàn)勝,盛行

surmount　v.克服，· 戰(zhàn)勝，· 越過

transcend　v.超越，· 勝過

tie　n.不· 分勝負(fù)　v.與成平局

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