Manypeoplebelievetheglarefromsnowcausessnowblindnenss.Yet,darkglassesornot,theyfindthemselvessufferingfromheadachesandwateringeyes,andevensnowblindness,whenexposedtoseveralhoursof"snowlight".
TheUnitedStatesArmyhasnowdeterminedthatglarefromsnowdoesnotcausesnowblindnessintroopsinasnow-coveredcountry.Rather,aman'seyesfrequentlyfindnothingtofoucsoninabroadexpanseofbarrensnow-coveredterrain.Sohisgazecontinuallyshiftsandjumpsbackandforthovertheentirelandscapeinsearchoftsomethingtolookat.Findingnothing,hourafterhour,theeyesneversotpsearchingandtheeyeballsbecomesoreandtheeyemusclesache.Natureoffsetsthisirritationbyproducingmoreandfluidwhichcoverstheeyeball.Thefluidcoverstheeyeballinincreasingquantityuntilvisionblurs,thenisobsured,andtheresultistotal,eventhoughtemporary,snowblindness.
ExperimentsledtheArmytoasimplemethodofovercomingthisproblem.Scoutsaheadofamainbodyoftroopsaretrainedtoshakesnowfromevergreenbushes,creatingadottedlineastheycrosscompletelysnow-coveredlandscape,Eventhescoutsthemselvesthrowlightweight,darkcoloredobjectsaheadonwhichtheytoocanfocus.Themenfollowingcanthenseesomething.Theirgazeisarrested.Theireyesfocusonabushandhavingfoundsomethingtosee,stopscouringthesnow-blanketedlanscape.Byfocusingtheirattentionononeobjectatatime,themencancrossthesnowwithoutbecominghopelesslysnowblindorlost.Inthiswaytheproblemofcrossingasolidwhiteterrainisovercome.
1.Topreventheadaches,wateringeyesandblindnesscausedbytheglarefromsnow,darkglassesare_____.
2.Whentheeyesaresoretearsareproducedto________.
3.Snowblindnessmaybeavoidedby_______.
a.concentratingtothesolidwhiteterrain
b.searchingforsomethingtolookatinsnow-coveredterrain
c.providingtheeyeswithsomethingtofoucson
d.coveringtheeyeballswithfluid
4.Thescoutsshakesnowfromevergreenbushesinorderto_______.
a.bivethemenbehindsomethingtosee
c.warmthemselvesinthecold
d.preventthemenbehindfromlosingtheirway
5.Asuitabletitleforthispassagewouldbe_______.
a.snowblindnessandhowtoovercomeit
b.natrue'scureforsnowblindness
d.snowvision
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