问答题爱使人产生一种安全感，爱使人对所爱的人产生一种安全感、信任感。它总是使双方在这种新的关系中有一种相互受益的感觉。(security, trust, involve, mutual)

填空题If an animal’s brain is kept active and stimulated, ______________.

填空题When the frontal lobes of the brain are affected by aging, there is a gradual deterioration in ________.

填空题If a person is under stress, ________ may become more frequent.

填空题Scientists do not understand why people’s ________ decline at different rates.

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填空题Absent-mindedness is not necessarily ________.

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问答题What can be inferred from the text about the master teacher scheme