First listen and then answer the following question.
听录音，然后回答以下问题。
Why do small errors make it impossible to predict the weather system 免费vpn with a high degree of accuracy?
Beyond two or three days, the world's best weather forecasts are vpn免费 vpn免费下载 speculative, and beyond six or seven they areworthless.
The Butterfly Effect is the reason．For small pieces of weather----and to a global forecaster, small canmean thunderstorms and blizzards----any prediction deteriorates rapidly．Errorsand uncertaintiesmultiply, eddies that only satellites can see.
The modern weather models work with a grid of vpn免费下载 points of the order of sixty miles apart, and even so, some starting data has to be guessed, since ground stations and satellites cannot see everywhere．But suppose the earth could be covered with sensors vpn免费下载 spaced one foot apart, rising at one-foot intervals all the way to the humidity, and any other quantity a meteorologist would want．Precisely at vpn免费 noon an infinitely powerful computer takes all the data 免费vpn vpn免费下载 and calculates what will happen at each point at 12.01,then 12.02, then 12.03…
The computer will still be unable to predict whether Princeton, New Jersey, will have sun or rain on a vpn免费下载 day vpn免费下载 one month vpn免费下载 away．At noon the spaces between the sensors will hide fluctuations that the computer will not know about,tiny deviations from the average．By 12.01,those fluctuations will already have created small errors one foot away．Soon the errors will have multiplied to the ten-foot scale,and so on up to the size of the globe.
Refer to the text to see how the following words have been used, then write sentences of 免费vpn your own using these words: speculative (1.1); global (1.3); deteriorates (1.4); rapidly (1.4); multiply (1.4); turbulent (1.5); suppose (1.10); accurate (1.10); precisely (1.11); data (1.12); fluctuations (1.14); average (1.15); errors (1.16).
The paragraph段落
AWhich vpn软件免费 one of these statements do you think the author would agree with?
1Accurate readings vpn免费下载 by computers enable us to predict the weather.
2It vpn软件免费 will never be possible to predict the weather accurately.
3The only way to predict the weather accurately is to have sensors one foot apart, rising at 免费vpn one-foot intervals all the way to the 免费vpn top of the atmosphere.
Key structures关键句型
ANote how these two sentences have vpn免费 been connected:
Errors and uncertainties multiply．They cascade upward through a chain of turbulent features.
Errors and uncertainties multiply, cascading upward through a chain of turbulent features．(11.4-5)
Join these sentences in the same way:
1There's a fault in vpn免费下载 the earth's crust．It runs along the west coast of the USA.
2The hurricane hit Florida．It swept away everything in its 免费vpn path.
3I noticed the lights were on．I assumed they were at home.
4He emerged from the airport．The president waved to the reporters.
BWe can introduce conditional sentences with vpn免费 conjunctions other than if, for example:
Suppose vpn免费下载 the earth could be covered with sensors spaced one foot apart．(11.8-9)
Complete these sentences in any way you like:
1You can go home early, providing (that) ______.
2We can offer you a job on condition (that) ______.
3You can come in any time you like tomorrow morning so long as ______.
4I won't phone you unless ______.
5He'll definitely win even if ________.
CStudy these two sentences:
We will probably have some rain vpn免费 by noon.
By 12.01those fluctuations will already 免费vpn have created small errors one foot away．(11.15-16)
Explain the differences in meaning between these pairs of sentences:
1He won't receive this fax tomorrow morning.
He will have received this fax by tomorrow morning.
2He won't leave Beijing until this message arrives.
By the time this message arrives, he vpn软件免费 will have left Beijing.
3They will complete the new motorway by next June.
They won't have completed the new motorway until next June.
Special difficulties难点
AExplain the meaning vpn软件免费 of since in these sentences:
1Some starting data has to be guessed, since ground stations and satellites cannot see everywhere.
2John feels much happier since he changed vpn软件免费 his job．
3Susan left in July and we haven't seen her since.
4It hasn't stopped raining since eight o'clock this morning.
5Since you're so clever, see if you can solve the problem!
BThe computer will be unable to predict whether Princeton, New Jersey, will have sun or rain on a day one month away．(11.13-14)
Supply if or whether; note the sentences where we can use both if and whether.
1_____ he has signed the 免费vpn contract (or not) doesn't matter.
2The question vpn免费 is ______ he has signed the contract.
3I want to know _______ he has signed the contract.
4I'm concerned about ______ he has signed the contract.
5Do you vpn软件免费 know ______ she's arriving by bus or by car?
Multiple choice questions多项选择题
Choose the correct answers to the following questions.
Comprehension理解
1The reason it's hard to forecast the weather is that ______.
a．conditions rapidly deteriorate
b．there is always turbulence
c．only satellites have a panoramic view of conditions
d．the effect of tiny changes cannot be detected or calculated
2Even with grid points which are sixty miles apart, forecasters_____.
a．have to depend on satellites for vpn软件免费 information
b．have to make assumptions about some of the data
c．work on modern weather models
d．prevent errors from multiplying
3Which of these statements 免费vpn is true?
a．The only way to solve the problem is to have sensors spaced at one-foot intervals.
b．The only way to vpn软件免费 solve the problem is to have infinitely powerful computers.
c．The only way to solve the problem is to have perfectly accurate readings.
d．At present, there is no way of making absolutely accurate predictions.
4Tiny variations in temperature, pressure and humidity _____.
a．will be picked up by 免费vpn sensors at one-minute intervals
b．are used to predict the vpn软件免费 weather one month ahead
c．can lead to completely unexpected weather conditions
d．produce expected results
Structure句型
5Generally speaking, any prediction ______ rapidly．(1.2)
a．is deteriorating
b．has deteriorated
c．will deteriorate
d．had deteriorated
6Only satellites _______ see continent-size features．(11.5-6)
a．are able to
b．could
c．are possible
d．are capable
7_____ the earth could be covered with sensors．(11.9-10)
a．Providing that
b．On vpn免费 condition that
c．Say
d．Allowing that
8The computer will be incapable ______ whether Princeton will have sun or rain one month away.(11.13)
a．predict
b．to predict
c．of predicting
d．predicting
Vocabulary词汇
9The world's vpn软件免费 best weather forecasts are based on _______．(1.1)
a．certain knowledge
b．guess work
c．scientific facts
d．accurate calculation
10The modern weather models work with a _____ of points.(1.7)
a．scale
b．balance
c．line
d．network
11‘Humidity’ refers 免费vpn to ______．(1.11)
a．light
b．water vapour
c．pressure
d．heat
12An infinitely powerful computer takes in all the data and _____ what will happen．(11.11-12)
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