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  Scientists have discovered that the brain can make its own drugs.The brain contains peptides,a protein substance.Peptides can act directly on the brain to change aspects of mental activity.There are peptides that may change or improve,for example,creativity, intelligence,imagination,and memory.Peptides have a great capacity to stimulate the brain to conquer deficiencies.They also improve the qualities of memory and learning already in the brain.They hold the secret to mood and emotion.Some day the peptides may be the chemical way to create better and more efficient brains.

  科学家们业已发现，______。脑中含有肽______一种蛋白质。肽能直接作用于大脑，______。例如，有些肽就能够改变或提高创造力、智力、想像力和记忆力。肽具有一种______。它也能改善大脑已有的记忆力和学习素质。______。将来有一天，肽可能成为改善和提高大脑效率的一种化学手段。