2021版高考英语新课程译林版一轮复习训练：Step 4 必修5 Unit 2 The envir.pdfVIP

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核心素养培养学生“生态文明”意识:人与自然和谐相处、良性循环,

让学生形成热爱自然亲近自然,保护自然的情操和品德;从我做起,从

身边事做起,学会保护环境。

高考链接2019·全国卷Ⅰ完形填空·;2019·北京高考D;·2019·天津高

考C;·2019·浙江6月高考C;·2018·全国卷ⅠD;2018··浙江高考B;·

2017·全国卷ⅡD;2017··全国卷ⅠB;2017··全国卷ⅢC·

Ⅰ.话题与高考阅读理解

(2019·天津高考C)·

Howdoesanecosystem(生态系统)work?Whatmakesthe

populationsofdifferentspeciesthewaytheyare?Whyarethereso

manyfliesandsofewwolves?Tofindananswer,scientistshavebuilt

mathematicalmodelsoffoodwebs,notingwhoeatswhomandhow

mucheachoneeats.

Withsuchmodels,scientistshavefoundoutsomekeyprinciples

operatinginfoodwebs.Mostfoodwebs,forinstance,consistof

manyweaklinksratherthanafewstrongones.Whenapredator(掠食动

物)alwayseatshugenumbersofasingleprey(猎物),thetwospeciesare

stronglylinked;whenapredatorlivesonvariousspecies,theyare

weaklylinked.Foodwebsmaybedominatedbymanyweaklinks

becausethatarrangementismorestableoverthelongterm.Ifa

predatorcaneatseveralspecies,itcansurvivetheextinction(灭绝)of

oneofthem.Andifapredatorcanmoveontoanotherspeciesthatis

easiertofindwhenapreyspeciesbecomesrare,theswitchallowsthe

originalpreytorecover.Theweaklinksmaythuskeepspeciesfrom

drivingoneanothertoextinction.

Mathematicalmodelshavealsorevealedthatfoodwebsmaybe

unstable,wheresmallchangesoftoppredatorscanleadtobigeffects

throughoutentireecosystems.Inthe1960s,scientistsproposedthat

predatorsatthetopofafoodwebha