根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多途选项。

Laser(激光)isshortforLightAmplificationbyStimulatedEmissionofRadiation．Laserlightisdifferentfromdaylightorelectriclights．Industryputlaserstoworkalmostimmediatelyaftertheywereinventedinnineteensixty．1．

Thefirstmedicaloperationusingalasertookplacetheyearfollowingitsinvention．DoctorsCharlesCampbellandCharlesKoesterusedalasertoremoveatumorfromapatient'seyeatColumbia-PresbyterianHospitalinNewYorkCity．2．

Lasershavemademeasurementanexactscience．Astronomershaveusedlaserstomeasurethemoon'sdistancefromEarth．3．Forexampledrawingaperfectlylevelstraightlineonaconstructionsiteiseasyusingalaser．

4．Andthejewelryindustryuseslaserstowriteonthesurfaceoftheworld'shardestsubstancediamonds．

Lasersarefoundinmanyproductsusedalmosteverywhere．Overonehundredyearsagowritersimaginedthatbeamsoflightcouldbepowerfulweapons．Todaylasersguidemissilesandbombs．Americandefensecompaniesareworkingongiantlasergunsrecognizabletosciencefictionfanseverywhere．5．

ScientificAmericanmagazinesayshugelasersturnonlyabouttwentytothirtypercentoftheenergytheyuseintoalaserbeam．Therestislostasheat．

Thathasnotstoppedscientistsfromworkingtoperfectpowerfullasersthatonedaymaybeabletoshootmissilesoutofthesky．

A．Butweaponswerenotthefirsttouseitonthelist．

B．Alllasershaveseveralthingsincommon．

C．Mappersandbuildersuselasertechnologyeveryday．

D．Buttherearetechnologicaldifficulties．

E．Lasershavealsochangedthewaywecommunicate．

F．Manufacturershaveusedlasersforyearstocutandjoinmetalparts．

G．Sincethendoctorshaveusedlaserstocutandremovetissuesafelywithlittleriskofinfections．