单项选择题
【案例分析题】
Man is the only animal that laughs.Why is this true？What makes us respond as we【C1】______to pleasurable experiences？What is the history of this ’happy convulsion’as someone once【C2】______it.and just what is its function？
We are not short【C3】______theories to explain the mystery，for centuries，biologists，psychologists，and medical men have【C4】______a definitive explanation of laughter.One writer theoried that its function is to intimidate others or to gain stature【C5】______them by humiliating them.Another took the opposite view that we laugh in order not to cry.A psychologist offered the explanation that laughter functions as a remedy【C6】______painful experiences，and that it serves to defend a person【C7】______what the psychologist termed ’the many minor pains【C8】______which man is exposed’，that the seventeenth century，a writer set【C9】______the theory that we laugh when we compare ourselves with others and’find ourselves superior；in effect，we laugh at the infirmities of others.
【C10】______every theory has been concerned with either the structure or the function of laughter，【C11】______relatively few have been devoted【C12】______the question.of its origin.I propose to offer a theory which，so far as I am 【C13】______，has not previously been set forth：that only those animals capable of speech are capable of laughter，and that therefore man，being the only animal that【C14】______，is the only animal that laughs.
Those of us who have observed Chimpanzees closely feel quite confident that the chimpanzee occasionally【C15】______behavior.that looks very much like a primitive precursor of human laughter.This behavior，however，has been observed only in a human【C16】______；whether or not it occurs under natural【C17】______is dubious；but the【C18】______fact that under any condition an ape is capable of such behavior.is【C19】______more than passing【C20】______for does it not indicate that early man had the rudiments of laughter？
【C1】（）
