AremarkablevarietyofinsectsliveinthisplanetMorespeciesofinsectsexistthanallotheranimalspeciestogether.Insectshavesurvivedonearthformorethan300millionyears,andmaypossesstheabilitytosurviveformillionsmore.
Insectscanbefoundalmosteverywhere--onthehighestmountainsandonthebottomofrushingstreams,inthecoldSouthPoleandinbubblinghotsprings.Theydigthroughtheground,jumpandsinginthetrees,andrunanddanceintheair.Theycomeinmanydifferentcolorsandvariousshapes.Insectsareextremelyusefultohumans,pollinating(授粉)ourcropsaswellasflowersinmeadows,forests,desertsandotherareas.Butlicksandsomeinsects,suchasmosquitoesandfleas,cantransmitdisease.
Therearemanyreasonswhyinsectsaresosuccessfulatsurviving.Theiramazingabilitytoadaptpermitsthemtoliveinextremerangesoftemperaturesandenvironments.Theoneplacetheyhavenotyetbeenfoundtoanymajorextentisintheopenoceans.Insectscansurviveonawiderange,ofnaturalandartificialfoods—paint,pepper,glue,books,grain,cotton，otherinsects,plantsandanimalsBecausetheyaresmalltheycanhideintinyspaces.
Astrong,hardbutflexibleshellcoverstheirsoftorgansandisresistanttochemicals,waterandphysicalimpact.Theirwingsgivethemtheoptionofflyingawayfromdangeroussituationsortowardfoodormales.Also,insectshaveanenormousreproductivecapacity:AnAfricanantqueencanlayasmanyas43,000eggsaday.
Anotherreasonfortheirsuccessisthestrategyofprotectivecolor.Aninsectmayberightbeforeoureyes,butnearlyinvisiblebecauseitiscleverlydisguisedlikeagreenleaf,lumpofbrownsoil,graylichen(青苔),aseedorsomeothernaturalobjectSomeinsectsusebright,boldcolorstosendwarningsignalsthattheytastebad,stingorarepoison.Othershavewingpatternsthatlookliketheeyesofahugepredator,bitter-tastinginsects;hungryenemiesarefooledintoavoidingthem.
练习题：
Choosecorrectanswerstothequestion:
1.InsectscanbefoundinlargeamountsinthefollowingplacesEXCEPT_____.
A.onthemountainswithlittleair
2.Insectsprotectthemselvesfromchemicalsby_______
C.flyingawaywhennecessary
3.Someinsectsdisguiselikenaturalobjectssoasto______
A.frightenawaytheirenemies
4.Thepassagementionsthatinsects______.
A.canbefoundinanyextremeenvironments
B.havesurvivedlongerthananyothercreatures
C.canbefedonanynaturalorman-madefoods
D.areimportantforthegrowthofcropsandflowers
5.Thepassageismainlyabout______
A.howinsectssurviveindifferentplaces
B.whyinsectscansurvivesosuccessfully
C.whatinsectscandototheenvironment
D.whereinsectscanbefoundinquantity
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