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
a juggler
agricultural steel
allochthonic ground water
ampersands
angiospermous wood
antirheoscope
biogecchemistry
bone-up
boudewijn kanaal
brages
burglar alarm system
cam journal
chordal node
comparison interval
crystal ballsmanship
cut it short
Cxorvotone
daystrom power plant automation language (dapal)
De Steeg
demand report
descriptive anthropologies
DGAF
disrank
district attorneys
dot system
dry forest zone
Elaeagnus tutcheri
elisia
endo('s) agar
enlighting
flat-tax
G stone
garnet-mica schist
gifford
hand hackle
harnes(s)ing
heavy oil partial oxidation process
heemantic
herculaneums
hexamminecobalt (III)chloride
horizontal position of welding
hycanthone
hygrophorus borealiss
instrument tube routing
iridium(vi) selenide
Kifuli
knocked down condition
lancaster method of instruction
lapsus linguae
latrans
lifetaker
lip swelling
long-term credit facility
maritime buoyage
Marmagao(Mormugao)
median plates of wingbase
microthrombi
minimization of Boolean function
MittelEuropean
moulded shoes
multibit branch
neutral absorption
next generation Internet
Nicholas, Saint
OCTT
olinton
PBIB
Pentaceros
phenylalanine aminotransferase
place under restraint
polystichum falcatum
precise orientation
primary head vein
Puerto Alfonso
recovery pending
red alarm light
relief grinding
response to
resultant tool force
ringing pilot lamp
round bottomed flask
Royal Naval Reserve
runoff erosion
safety car
salmon-eye locus
Sandro
sarpo
scroll-paintings
self-presentations
septenary notation
split run
spoil the Egyptians
Spondias pinnata Kurz
straight flange design
street corners
Sumprabum
super sifter
tentative standard
underground river
victoria's secret
wear inhibitor
wh-what