Security technology: A new type of computerised photofit system takes a novel evolutionary approach to generating images of suspects. If you have ever tried to describe someone's face in detail, you will understand why the "photofit" composite images used by the police look so dodgy. In recent years, computerised "E-Fit" systems have helped improve the accuracy of these images by allowing witnesses to choose from a wider range of facial features. But researchers at the University of Stirling in Scotland found that, despite these improvements, people still have a hard time constructing recognisable faces--especially if there is a delay of more than a few hours between seeing the face and generating the composite.
The problem is that people tend to recognise faces as whole entities, rather than as separate features. So picking from a range of eyes, noses and mouths is not necessarily the most suitable approach, says Charlie Frowd, a psychologist at the University of Stirling. Next year, however, British police are expected to begin trials of a new computerised system, called EvoFIT, developed by Dr. Frowd and his colleague Peter Hancock. It uses an evolutionary approach, known as a genetic algorithm, to "evolve" faces rather than piece them together.
"The process is entirely non-verbal and takes a fraction of the normal time", claims Dr. Frowd. A witness is shown an array of 60 different faces with random features. Having studied them closely, the witness is asked to choose the six images that most closely resemble the person they are trying to describe. These six are then used to generate another set of 60, by switching featurees between some of the images and by making random changes to others. The witness is then asked to repeat the task, whereupon a new batch of faces is generated, and so on. In evolutionary terms, this process is known as "genetic crossover and mutation", and is a powerful way to search a large number of possibilities for a particular solution. By allowing the user to steer the selection process, the program is able to generate a good likeness for the original face after just a few cycles.
In one of its early versions, EvoFIT was used by police in Northampton shire who were trying to catch a violent attacker. The attacker was never caught, but the senior investigating officer, Superintendent Paul Spick, says the witness involved found the new software much quicker and easier to use than traditional E-Fit systems. It was also more accurate, the final image caused the witness visible distress when displayed. A further important advantage of EvoFIT over traditional composites is that an image can be generated even if the witness can only provide a sketchy verbal description.
The researchers have since made a number of further improvements to their system and are now in the process of commercializing it in partnership with ABM, a British firm which supplies police forces with photofit, one of the leading computerized composite systems. The images are more realistic, and the system can generate three-quarter angle views of the face, which are easier to distinguish than direct frontal views, says Dr. Frowd.
His team has also found that by combining the images generated by different witnesses, or even from a single witness, it is possible to get an even better likeness. This could be particularly useful when multiple witnesses come forward and the police are unsure which of the images they produce is the most accurate. In the latest version, witnesses are given a selection of face shapes to choose from before facial features are added.

单选题 The word "composite" in paragraph i is closest in meaning to ______.
A. mixture B. compose C. find D. system

单选题 The word "dodgy" in paragraph 1 could best be replaced by ______.
A. evasive B. competitive
C. urgently D. unlike

单选题 Why does the author mention "especially if there is a delay of more than a few hours..." in paragraph 1? ______
A. Tend to have a hard time constructing recognizable faces.
B. Tend to have a hard time telling people.
C. Tend to have a hard time helping police.
D. Try to resemble people.

单选题 According to the passage, which of the following is true? ______
A. Faces are more often to be remembered as whole entities.
B. Faces are not likely to be remembered as whole entities.
C. Faces are more likely to be recognized.
D. It can piece the facial features together based on witnesses' descriptions.

单选题 Which sentence below best expresses the essential information in the highlighted sentence in paragraph 3? Incorrect choices change the meaning in important ways or leave out essential information.
A. We can only find one particular solution in particular term, which we call "genetic revolutionary change".
B. It is difficult for us to find particular features and tell the faces because of "genetic crossover and mutation".
C. We have no idea to switch features between some of the images and by making random changes to others in evolutionary terms.
D. We can search a large number of the features and resolve difficuties in evolutionary terms, which we call "genetic revolutionary change".

单选题 According the passage, which of the following is true? ______
A. EvoFIT will have to address three questions though it looks promising so far.
B. EvoFIT will have to address two questions though it looks promising so far.
C. EvoFIT will have to address four questions though it looks promising so far.
D. EvoFIT will have to address one question though it looks promising so far.

单选题 The word "its" in paragraph 4 refers to ______.
A. EvoFIT B. photofit C. person D. attacker

单选题 The writer mentions a number of advantages of EvoFIT in paragraph 4 EXCEPT ______.
A. the user doesn't have to steer the selection process
B. it's a powerful way to search a large number of possibilities for a particular solution
C. it is quick and accurate in generating a good likeness for the original face
D. an image can be generated even if the witness can only provide a sketchy verbal description

单选题 According to paragraph 4, what are the improvements that EvoFIT researchers have made to the system except? ______
A. Giving witnesses a selection of face shapes to choose from before facial features are added.
B. Generating facial features after several rounds of selections.
C. Combining the images generated by different witnesses or even from a single witness.
D. Generating three-quarter angle views of the face.

单选题 Look at the four squares, , , and

单选题 The word "contaminate" in paragraph 8 could best be replaced by ______.
A. make unforgettable B. make clean
C. make large D. make impure

填空题 Directions: Complete the table below about how EvoFIT works in detail in the passage. This question is worth 3 points.
Genetic crossover and mutation
Step 1
·______
Step 2
·______
Step 3
·______
Step 4
·______
Step 5
·______

A. Ask the witness to choose the six images that closely resemble the person they try to describe.
B. Combine the results of different witnesses.
C. Switch features between some of the selected images or make random changes to others.
D. Add facial features to the selected face shapes.
E. Ask the witness to repeat the task and generate a new batch of faces.

F. Show the witness an array of 60 different faces with random features.

G. Ask the witness to decide the face shapes that they have in memory.

[H] Use the selected six images to generate another set of 60 and repeat the cycle.