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    Naps-short sleeps during the day-may improve memory, experts said recently.

    New research conducted by brain researcher Avi Karni of the University of Haifa in Israel explores

the possibility that naps help lock in sometimes long-term memories. "We still don't know exactly how

memory system works during sleep, but the results of this research suggest it is possible to speed up

memory consolidation (巩固)," Karni said. Long-term memory refers  to memories that stay with us for

years, such as "what" memories-a car accident that happened yesterday-or "how to" memories, such as

one's learned ability to play the pianos.

     Karni, also one of the authors of the study published in a recent issue of the journal Nature

Neuroscience, instructed participants to learn a difficult set of finger games, then divided the study

subjects into two groups: one that napped for an hour, and one that didn't. The people who took an

afternoon snooze showed obvious improvement in their performance by that evening.

     "After a night's sleep the two groups were at the same level, but the group that slept in the afternoon

improved much faster than the group that stayed awake," Karni said. And the study also showed just

how much faster a 90-minute nap could help lock in long-term memories. "Daytime sleep can shorten the

time 'how to' memory weakens and forgetting starts,"Karni said, "Instead of 6 to 8 hours, the brain

consolidated the memory during the 90-minute nap."

1. We can learn from the article that ________.

A. the new research has discovered the memory process during the sleep

B. taking a nap helps improve both long-term and short-term memories

C. Karni's findings are based on comparisons between two groups of participants

D. people who take a nap will never forget "how to" skills once they are learned

2. The underlined word "subjects" in paragraph 3 probably mean________. 

A. the people being tested in the study

B. the people carrying out the study

C. the topics being discussed in the study

D. the areas of knowledge being studied

3. The text is most probably taken from ________.

A. a newspaper report    

B. a library guide 

C. a project handbook    

D. a science site