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ience； in the form of behavioral psychology； supports that wisdom。 But such behavioral studies cannot distinguish between two competing theories of why sleep is good for the memory。 One says that sleep is when permanent memories form。 The other says that they are actually formed during the day； but then “edited” at night； to flush away what is superfluous。
To tell the difference； it is necessary to look into the brain of a sleeping person； and that is hard。 But after a decade of painstaking work； a team led by Pierre Maquet at Liege University in Belgium has managed to do it。 The particular stage of sleep in which the Belgian group is interested in is rapid eye movement （REM） sleep； when brain and body are active； heart rate and blood pressure increase； the eyes move back and forth behind the eyelids as if watching a movie； and brainwave traces resemble those of wakefulness。 It is during this period of sleep that people are most likely to relive events of the previous day in dreams。
Dr。 Maquet used an electronic device called PET to study the brains of people as they practiced a task during the day； and as they slept during the following night。 The task required them to press a button as fast as possible； in response to a light coming on in one of six positions。 As they learnt how to do this； their response times got faster。 What they did not know was that the appearance of the lights sometimes followed a pattern — what is referred to as “artificial grammar”。 Yet the reductions in response time showed that they learnt faster when the pattern was present than when there was not。
What is more； those with more to learn （i。e。； the “grammar”； as well as the mechanical task of pushing the button） have more active brains。 The “editing” theory would not predict that； since the number of irrelevant stimuli would be the same in each case。 And to eliminate any doubts that the experimental subjects were learning as opposed to unlearning； their response times when they woke up were even quicker than when they went to sleep。
The team； therefore； concluded that the nerve connections involved in memory are reinforced through reactivation during REM sleep； particularly if the brain detects an inherent structure in the material being learnt。 So now； on the eve of that crucial test； maths students can sleep soundly in the knowledge that what they will remember the next day are the basic rules of algebra and not the incoherent talk from the radio next door。
26。Researchers in behavioral psychology are divided with regard to
＇A＇ how dreams are modified in their courses。 ＇B＇ the difference between sleep and wakefulness。
＇C＇ why sleep is of great benefit to memory。 ＇D＇ the functions of a good night’s sleep。
27。As manifested in the experimental study； rapid eye movement is characterized by
＇A＇ intensely active brainwave traces。 ＇B＇ subjects’ quicker response times。
＇C＇ complicated memory patterns。 ＇D＇ revival of events in the previous day。
28。By referring to the artificial grammar； the author intends to show
＇A＇ its significance in the study。 ＇B＇ an inherent pattern being learnt。
＇C＇ its resemblance to the lights。 ＇D＇ the importance of night’s sleep。
29。In their study； researchers led by Pierre Maquet took advantage of the technique of
＇A＇ exposing a long…held folk wisdom。 ＇B＇ clarifying the predictions on dreams。
＇C＇ making contrasts and comparisons。 ＇D＇ correlating effects with their causes。
30。What advice might Maquet give to those who have a crucial test the next day？
＇A＇ Memorizing grammar with great efforts。 ＇B＇ Study textbooks with close attention。
＇C＇ Have their brain images recorded。 ＇D＇ Enjoy their sleep at night soundly。
Text 3
This line of inquiry did not begin until earlier this month — more than three months after the accident — because there were “too many emotions； too many egos；” said retired Adm。 Harold Gehman； chairman of the Columbia Accident Investigation Board。
Testifying before the Senate Commerce Committee； Gehman said this part of his inquiry was in its earliest stages； starting just 10 days ago。 But Gehman said he already has concluded it is “inconceivable” that NASA would have been unable or unwilling to attempt a rescue for astronauts in orbit if senior shuttle managers and administrators had known there was fatal damage to Columbia’s left wing。
Gehman told reporters after the hearing that answers to these important questions could have enormous impact； since they could place in a different context NASA’s decisions against more aggressively checking possible wing damage in the days before Columbia’s fatal return。
Investigators believe breakaway insulating foam damaged part of Columbia’s wing shortly after liftoff； allowing superheated air to penetrate the wing during its fiery reentry on Feb。1； melt it from inside。
Among those decisions was the choice by NASA’s senior shuttle managers and administrators to reject offers of satellite images of possible damage to Columbia’s left wing before the accident。 The subject dominated the early part of Wednesday’s hearing。
Gehman complained managers and administrators “missed signals” when they rejected those offers for images； a pointedly harsh assessment of the space agency’s inaction during the 16…day shuttle mission。
“We will attempt to pin this issue down in our report； but there were a number of bureaucratic and administrative missed signals here；” Gehman told senators。 “We’re not quite so happy with the process。”
The investigative board already had recommended that NASA push for better coordination between the space agency and military offices in charge of satellites and telescopes。 The U。S。 National Imagery and Mapping Agency in March agreed to regularly capture detailed satellite images of space shuttles in orbit。
Still； Gehman said it was unclear whether even images from America’s most sophisticated spy satellites might have detected on Columbia’s wing any damage；