C9-T3-R3

1.题干：an explanation of the factors affecting the transmission of information

（C9-T3-R3 T27）

原文：Information theory generalises this idea via theorems that capture the effects of noise with mathematical precision. In particular, Shannon showed that noise sets a limit on the rate at which information can pass along communication channels while remaining error-free.

同义替换：

An explanation --- generalises this idea

Factors --- effects

The transmission of information --- information can pass along communication channels

 

2.题干：an example of how unnecessary information can be omitted

（C9-T3-R3 T28）

原文：As mobile phone text messages like ‘I CN C U’ show, it is often possible to leave out a lot of data without losing much meaning.

同义替换：

An example --- mobile phone text messages like ‘I CN C U’

Unnecessary information --- leave out a lot of data

Be omitted --- without losing much meaning

 

3.题干：a reference to Shannon’s attitude to fame（C9-T3-R3 T29）

原文：While at Bell Laboratories, Shannon developed information theory, but shunned the resulting acclaim.

同义替换：

Shannon’s --- Shannon

Attitude to fame --- shunned the resulting acclaim

 

4.题干：details of a machine capable of interpreting incomplete information

（C9-T3-R3 T30）

原文：The Voyager spacecraft transmitted data using codes which added one extra bit for every single bit of information; the result was an error rate of just one bit in 10,000 - and stunningly clear pictures of the planets.

同义替换：

A machine --- the Voyager spacecraft

capable of interpreting incomplete information --- stunningly clear pictures of the planets

 

5.题干：a detailed account of an incident involving information theory

（C9-T3-R3  Q31）

原文：In April 2002 an event took place which demonstrated one of the many applications of information theory.

同义替换：

A detailed account --- demonstrated one

An incident --- an event

Involving --- applications of

 

6.题干：a reference to what Shannon initially intended to achieve in his

research

（C9-T3-R3 Q32）

原文：This all seems light years away from the down-to-earth uses Shannon originally had for his work, which began when he was a 22-year-old graduate engineering student at the prestigious Massachusetts Institute of Technology in 1939. He set out with an apparently simple aim: to pin down the precise meaning of the concept of ‘information’.

同义替换：

Shannon initially --- Shannon originally

Intended to achieve --- set out with an apparently simple aim

 

7.题干：The probe transmitted pictures of both …and …,（C9-T3-R3 Q33）

原文：The space probe, Voyager I, launched in 1977, had sent back spectacular images of Jupiter and Saturn…

同义替换：

The probe --- the space probe

Transmitted --- had sent back

Pictures --- spectacular images of

 

8.题干：then left the…（C9-T3-R3 Q34）

原文：and then soared out of the Solar System on a one-way mission to the stars.

同义替换：

Left --- soared out of

 

9.题干：The freezing temperatures were found to have a negative effect on

parts of

the space probe.（C9-T3-R3 Q34-35）

原文：After25 years of exposure to the freezing temperatures of deep space, the probe was beginning to show its age.

同义替换：

Were found --- was beginning to

Have negative effect on --- show its age

The space probe --- the probe

 

10.题干：Scientists feared that both the …and …were about to stop

working.

（C9-T3-R3 Q35）

原文：Sensors and circuits were on the brink of failing and NASA experts realised that they had to do something or lose contact with their probe forever.

同义替换：

Scientist --- NASA experts

Feared --- realised

Were about to stop working --- were on the brink of failing

 

11.题干：The only hope was to tell the probe to replace them with…- but

distance made communication with the probe difficult.（C9-T3-R3 Q36）

原文：The solution was to get a message to Voyager I to instruct it to use spares to change the failing parts. With the probe 12 billion kilometres from Earth, this was not an easy task.

同义替换：

The only hope --- the solution

To tell the probe --- to get a message to Voyager I

Replace …with …--- use …to change

Distance --- 12 billion kilometres

Difficult --- not an easy task

 

12.题干：A …was used to transmit the message at the speed of light.

（C9-T3-R3 Q37）

原文：By means of a radio dish belonging to NASA’s Deep Space Network, the message was sent out into the depths of space. Even travelling at the speed of light, it took over 11 hours to reach its target, far beyond the orbit of Pluto.

同义替换：

A…was used --- by means of a …

To transmit the message --- the message was sent out

At the speed of light --- travelling at the speed of light

 

13.题干：The message was picked up by the probe and the switchover took

place.（C9-T3-R3 Q37）

原文：Yet, incredibly, the little probe managed to hear the faint call from its home planet, and successfully made the switchover.

同义替换：

Was picked up --- hear the faint call

Took place --- successfully made

 

14.题干：The concept of describing something as true or false was the starting

point for Shannon in his attempts to send messages over distances.

（C9-T3-R3 Q38）

原文：The most basic form of information, Shannon argued, is whether something is true or false - which can be captured in the binary unit, or ‘bit’, of the form 1 or 0.Having identified this fundamental unit, Shannon set about defining otherwise vague ideas about information and how to transmit it from place to place.

同义替换：

Describing --- having identified

The starting point --- the most basic form

Something as true or false --- something is true or false

Send messages over distances --- transmit it from place to place

 

15.题干：The amount of information that can be sent in a given time period is

determined with reference to the signal strength and noise level.（C9-T3-R3

Q39）

原文：This rate depends on the relative strengths of the signal and noise travelling down the communication channel, and on its capacity (its  ‘bandwidth’).

同义替换：

Is determined with reference to --- depends on

The signal strength and noise level --- the relative strengths of the signal and noise

Be sent --- travelling down

 

16.题干：Products have now been developed which can convey more

Information than Shannon had anticipated as possible.（C9-T3-R3 Q40）

原文：As recently as 1993, engineers made a major breakthrough by discovering so-called turbo codes - which come very close to Shannon’s ultimate limit for the maximum rate that data can be transmitted reliably, and now play a key role in the mobile videophone revolution.

同义替换：

Products --- the mobile videophone

Been developed --- made a major breakthrough by discovering

Convey more information --- come very close to Shannon’s ultimate limit for the maximum rate