时间:2018-12-31 作者:英语课 分类:英语听力文摘 English Digest


英语课

   What Makes White Gold White?


  Many people associate the metal gold with the color gold. But, some gold jewelry 1 is not golden at all: it’s white.
  Golden Color
  Gold is one of the heaviest and softest metals. Pure gold, called 24-carat gold, is so soft that it can be easily dented 2. In the movies, old-time prospectors 3 bite on yellow nuggets to see if they’re real gold because 24-carat gold will show a bite mark. In the real world, jewelers don’t want to use metal that can be dented so easily. So, most jewelry is actually an alloy 4 of gold with harder metals.
  Since pure gold is called 24-carat gold, an alloy of half gold and half other metals is called 12 carat gold, because, well, 12 is half of 24.

  Alloys 5
  If most gold jewelry is an alloy, why is some white and some yellow? The final appearance depends on the type of alloy metal used. Alloys made with white metals like silver, palladium and nickel create white-colored gold. Adding some copper 6 to the alloy will restore the yellow color, but too much copper can turn the gold reddish.
  The color of gold jewelry doesn’t reveal how much gold is in it — a piece of white gold may have the same number of carats as a piece of yellow gold. But, it has a different alloy metal, and so it has a different color.
  Unlike white gold, fool’s gold has no gold in it at all. It’s a mineral called iron pyrite. Black gold isn’t gold either, it’s oil. Which is also valuable, but doesn’t look as good on your fiancée’s finger.

n.(jewllery)(总称)珠宝
  • The burglars walked off with all my jewelry.夜盗偷走了我的全部珠宝。
  • Jewelry and lace are mostly feminine belongings.珠宝和花边多数是女性用品。
v.使产生凹痕( dent的过去式和过去分词 );损害;伤害;挫伤(信心、名誉等)
  • The back of the car was badly dented in the collision. 汽车尾部被撞后严重凹陷。
  • I'm afraid I've dented the car. 恐怕我把车子撞瘪了一些。 来自《简明英汉词典》
n.勘探者,探矿者( prospector的名词复数 )
  • The prospectors have discovered such minerals as calcite,quartz and asbestos here. 探矿人员在这里发现了方解石、石英、石棉等矿藏。 来自《简明英汉词典》
  • The prospectors have discovered many minerals here. 探矿人员在这里发现了许多矿藏。 来自辞典例句
n.合金,(金属的)成色
  • The company produces titanium alloy.该公司生产钛合金。
  • Bronze is an alloy of copper and tin.青铜是铜和锡的合金。
n.合金( alloy的名词复数 )
  • This is essentially a development of thoria dispersion strengthened nickel alloys. 这基本上是用二氧化钍弥散强度化的镍基合金。 来自辞典例句
  • The lack of deep hardening in these alloys negates their use. 这些合金缺乏深层硬化能力使它们无法利用。 来自辞典例句
n.铜;铜币;铜器;adj.铜(制)的;(紫)铜色的
  • The students are asked to prove the purity of copper.要求学生们检验铜的纯度。
  • Copper is a good medium for the conduction of heat and electricity.铜是热和电的良导体。
标签: 听力文摘
学英语单词
acceptance following construction
accuminating
ad hoc testing
address circuit
agneta
Ahunvar
all wave operation
allied
apparent chargeability
barter contract
be barking up the wrong tree
bedazzled
bengough-stuart process
biaxial stress
bioprocessing
bonitus
car dynamometer
carbon black dispersion
catalytic cycle oil
Chenonceaux
Choate Rosemary Hall
cleaner cell
crab walk
crawly
critical patch
cusp forms
davit
democratic personage
disabled soldier
discontinuous variate
doffing cylinder
double track directors system
e-2s
ebullioscopic method
electromicrokeratome
epigranite
ethyl methyl acetic acid
external comparison method
fibre molecule
firing time
floating dot
forward-deployed
fully bleached linen
FXR (flash X ray diffraction)
grandcamp
Headcorn
hogge
in the works
inchoate instrument
internal store
interneurone
kocel
land description
Las Tres Virgenes, Vol.
lay it on the line
Leontopodium pusillum
locally finite refinement
lock saw
lympho-epithelioma
Maister
match filter
meningitis serosa circumscripta cystica
methylsulfuric acid
mineys
moghra
mutually offsetting accounts
neutron slowing down theory
operating divisions
paghant
panned out
parella
periscope housing
peyotes
porcupinefishes
prevailing
re-convert
reactor neutron source
reason for living
recur
reminiscently
revelries
rice nursery
Roscoe
set shackle
shepherd's clock
silk screen printing method
Simulium vittatum
sleeptalks
sliding platform
solid guide
street values
sweep laser
tax equalization account
temperature-sensitive gene
temporary variable description
tetrapartile chromosome
Thalictrum omeiense
tzaricides
vegetable diastase
wef
well-integrateds
wooch