一支可在1500码远的地方精确射杀的武器开辟了全新的局面，令每个能够得到它的家族、部落都欢欣鼓舞。(accuracy, a whole new scene of, clan)

问答题这便增加了政府开支，而相应减少了本可以用来发展国家的经济资源。

问答题这些要求有点过头，一系列的争端也由此而起。(too much, ask, quarrel, origin)

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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