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【Itisonlyashinyyellowmetalbutitisoneofthemostvaluablethingsonearth.Sincethebeginningoftimemenhavelookedforthisextremelyvaluableitemgold.Goldissoftandeasytoformintodifferentobjects.】
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问题描述:

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?

[]

A.ValuableMetal.

B.LookingforGold.

C.JewelryandCoins.

D.WhatisKarat?

(2)Whichisnotthereasonwhygoldishighlyvaluable?

[]

A.Itcanbemadeintojewelry.

B.Itisnoteasilyfound.

C.Itissoftandshiny.

D.Itdoesn'trust(生锈)whenwet.

(3)Inordertomakeitstrongergoldisoftenmixedwith______.

[]

A.hardgold

B.coinsandjewelry

C.acids(酸)

D.othermetals

(4)Ifaringismarked12Kthenthepercentageofgoldis_____.

[]

A.12

B.50

C.25

D.24

凌海滨回答:
  答案:B;C;D;B
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