时间:2018-12-26 作者:英语课 分类:美国英语听力80篇


英语课

[00:06.37]The United States has a new official clock.

[00:10.95]The clock began operating late last year in the American city of Boulder,Colorado.

[00:18.39]Experts say the new clock is so exact that it will neither gain nor lose so much as one second in the next 20,000,000 years.

[00:30.82]Scientists with the National Institute of Standards and Technology developed the new atomic clock.

[00:39.47]The agency is part of the United States Department of Commerce.

[00:44.72]The new clock was built and tested in less than four years.

[00:49.92]It is now being used to measure the official world time, known as Coordinated 1 Universal Time.

[00:58.28]The clock measures time by counting the movements of atoms of the element cesium.

[01:05.72]The natural rate of movement of cesium atoms has been used to measure time since 1967.

[01:13.67]Researchers have found that cesium atoms move back and forth 2 at a rate of almost 9,200,000,000 times in one second.

[01:26.02]The new clock is less than two meters tall.

[01:30.98]This is how it works.

[01:33.31]First, a gas of cesium atoms is released in an empty container.

[01:39.55]All other matter has been removed from this vacuum chamber 3.

[01:45.06]Six beams of laser light are directed at the center of the chamber.

[01:50.86]The lasers slow the movement of the cesium atoms.

[01:55.83]The lasers force the atoms into a cloud of gas shaped like a ball.

[02:02.36]Two lasers push the ball of gas upward through a passage filled with microwave energy.

[02:10.17]Then,all of the lasers are turned off.

[02:13.69]Gravity pulls the ball of cesium atoms back down through the passage.

[02:20.23]The microwaves change some of the atoms.

[02:24.46]The microwaves cause some of the atoms to move quickly back and forth.

[02:30.62]Another laser causes the cesium atoms to produce light.

[02:35.48]The light is measured by special observation equipment.

[02:40.76]This process is repeated many times while different levels of mierowave energy are used.

[02:49.25]The researchers find a level of ehergy that makes the cesium atoms produce the most light.

[02:57.24]This is the rate of movement used to define one second.

[03:02.36]The new device replaces another atomic clock that has served as the official clock of the United States since 1993.

[03:12.21]The new clock is said to be three times more exact than the atomic clock it replaced



1 coordinated
adj.协调的
  • The sound has to be coordinated with the picture. 声音必须和画面协调一致。
  • The numerous existing statutes are complicated and poorly coordinated. 目前繁多的法令既十分复杂又缺乏快调。 来自英汉非文学 - 环境法 - 环境法
2 forth
adv.向前;向外,往外
  • The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
  • He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。
3 chamber
n.房间,寝室;会议厅;议院;会所
  • For many,the dentist's surgery remains a torture chamber.对许多人来说,牙医的治疗室一直是间受刑室。
  • The chamber was ablaze with light.会议厅里灯火辉煌。
学英语单词
absolute addresses
additive oil
antimony blende (kermesite)
arteria ileocolicas
Arteria suprarenalis inferior
astronomical position finder
atomic bomb hysteria
awaited
be in good company
Belcherville
Bonhams
Bonoua
Bratskoye
bridge type feedback
choke coupled magnetic amplifier
Ciproxin
conventional scale
cytopathogenic
daringometer
data-signaling-system
death benefit
Diltāwa
dimitars
dool
double end kiln
downfaulted
drift method
dysmetropsia
eger
electric operated fixture
eumeiosis
Farm Credit System
fluidextracts
gap estimate
genus Melissa
get scent
ghost-write
goblet with Southern Song imperial kiln type glaze
hartebeest
hypoplastic incisor
impetigines
institutional advertising
Irish architecture
Isle of White
keyword approach
kinematically admissible velocity field
kneeboards
kronenfeld
Mabechi-gawa
Mamertini
marking and packing
mating type
meshed gears
multi function device
Namib.
nephridial tubule
pan dulce
parability
patellar luxation
Permutit S K
perspirings
photodensitometry
pinealocytomas
polarily
power-laden
president-designate
private office layout
probenazole
pulmo-cutaneous vein
rag willow
razinodil
referring
register oneself
responding party
rhabdochaeta naevia
rubber johnny
samoilovich
scatterhoard
schmalensees
Sievert chamber
sleepy heads
spending cuts
stboes
stereographic technique
tappette
temporosphenoid
the cat s pyjamas
thermal insulating property
three-pressure stage turbine
toga virilis
toluidine blue method
tonic pain
tough nookies
tpn (triphosphopyridine nucleotide)
transit network identification
transport by container
truck mounted workover rig
undercut trimmer saw
ventriculitides
very lucky
Wendlandia jingdongensis
wise saw