Itisonlyashinyyellowmetalbutitisoneofthemostvaluablethingsonearth.Sincethebeginningoftimemenhavelookedforthisextremelyvaluableitemgold.
Goldissoftandeasytoformintodifferentobjects.Ifitgetswetitdoesnotrustlikeironorothermetals.Acids(酸)don'tchangeit.Oneimportantreasonwhygoldissovaluableisthatitisscarce.Becauseofitssoftnessgoldmustbecombinedwithothermetalsandsomakeithardenandgiveitstrength.Byhardeninggoldpeoplecanthenmakecoinsandjewelrywithit.Metalscommonlymixedwithgoldarenickel(镍)platinum(铂)andcopper.Goldjewelrybears(刻有)anumberandtheletterK.TheKmeanskarat(carat)whichisameasureoftheamountofpuregoldinthejewelry.Puregoldis24K.Thereforeanecklacewhichis14Kisfourteenpartsofgoldandtenpartsofothermetals.
Manycountriesmakeuseofgoldforcertaincoinsbutthispracticeisnotascommonnowasitoncewas.TheUnitedStatesforinstancestoppedmakinggoldcoinsin1933.
(1)Whichofthefollowingwouldbethebesttitleforthispassage?
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A.ValuableMetal.
B.LookingforGold.
C.JewelryandCoins.
D.WhatisKarat?
(2)Whichisnotthereasonwhygoldishighlyvaluable?
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A.Itcanbemadeintojewelry.
B.Itisnoteasilyfound.
C.Itissoftandshiny.
D.Itdoesn'trust(生锈)whenwet.
(3)Inordertomakeitstrongergoldisoftenmixedwith______.
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A.hardgold
B.coinsandjewelry
C.acids(酸)
D.othermetals
(4)Ifaringismarked12Kthenthepercentageofgoldis_____.
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A.12
B.50
C.25
D.24
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