It was a method favoured by the inventor Thomas Edison and the artist Salvador Dali.Waking from a nap exactly at the point before deep sleep in an effort to inspire creativity.
    Edison held a metal ball in his hand so that if he nodded off he would drop it and the sound would wake him.For Dali，it was a key landing on a plate.Now scientists have found that they might have been onto something.
    Researchers at the Paris Brain Institute studied people's ability to find a hidden rule in a maths puzzle.Identifying the trick would make solving the problem far simpler but to do so required thinking creatively.The scientists found that participants who had been woken just before falling into a deep sleep，using a technique like that used by Edison and Dali，were more likely to find the shortcut.
    This "twilight zone" is known as non-rapid eye movement sleep stage 1，or N _____ Scientists described it like an exaggerated form of mind-wandering，where dream-like thoughts fill the mind.It is thought that as people start to disengage （脫離） from their environment they can "freely watch their minds wander，while maintaining their ability to identify creative sparks （火花）".
    For the study 103 people were given a maths problem to solve.To reach the final answer they had to apply the rules step by step but，unknown to them，a "hidden rule" would allow them to bypass most of the steps and get to the solution much more quickly.The results showed that 83 percent of those in the N1 group had found the shortcut，compared with 31 percent in the group who were awake and 14 percent of those in a deep sleep.
    Researchers conclude that the brain activity common to the twilight zone between sleep and wakefulness set off creative sparks. "Although the neural mechanisms （神經(jīng)機(jī)制） involved are not yet known，our findings suggest that there is a creative sweet spot within the twilight zone，" said Dr Thomas Andrillon，co-author of the study.

（1）Why did the author mention "a metal ball" and "a key" in Paragraph 2？

A

A

A．To clarify a method.
B．To explain a theory.
C．To present a concept.
D．To make a comparison.
（2）What can we learn about "the twilight zone" from the text？

D

D

A．It prevents your mind from wandering.
B．It determines what your dreams will be like.
C．It is known as rapid eye movement sleep stage.
D．It is a state of being half asleep and half awake.
（3）What does "the shortcut" in Paragraph 5 refer to？

C

C

A．The maths problem.
B．The final answer.
C．The hidden rule.
D．The added step.
（4）What attitude may Dr Thomas Andrillon hold to the technique used by Edison and Dali？

D

D

A．Doubtful.
B．Critical.
C．Indifferent.
D．Favorable.