Ancient Greek philosopher Aristotle viewed laughter as“a bodily exercise precious to health.”But---_____some claims to the contrary,laughing probably has little influence on physical filness Laughter does_____short-term changes in the function of the heart and its blood vessels,____heart rate and oxygen consumption But because hard laughter is difficult to____,a good laugh is unlikely to have_____benefits the way,say,walking or jogging does.____,instead of straining muscles to build them,as exercise does,laughter apparently accomplishes the____,studies dating back to the 1930’s indicate that laughter.muscles,Such bodily reaction might conceivably help____the effects of psychological stress.Anyway,the act of laughing probably does produce other types of______feedback,that improve an individual’s emotional state.______one classical theory of emotion,our feelings are partially rooted_______physical reactions.It was argued at the end of the 19th century that humans do not cry______they are sad but they become sad when te tears begin to flow.Although sadness also_______tears,evidence suggests that emotions can flow_____muscular responses.In an experiment published in 1988,social psychologist Fritz Strack of the University of würzburg in Germany asked volunteers to____a pen either with their teeth-thereby creating an artificial smile–or with their lips，which would produce a（n）_____expression.Those forced to exercise their enthusiastically to funny catoons than did those whose months were contracted in a frown，_______that expressions may influence emotions rather than just the other way around____，the physical act of laughter could improve mood.
空格要求填入一个形容词，修饰后面的expression，并且这种表情是“当用嘴唇含住一支笔时”产生的，根据上下文可知两组人的表情是相反的，并且“当用牙咬住一支笔时可以制造一种假笑”，由此可推断“当用嘴唇含住一支笔时会产生一种失望的表情”，?这与后文中提到的“那些嘴唇皱着的人”相呼应，四个选项中?[B]excited“兴奋的”，[C]joyful“快乐的”，[D]indifferent“漠不关心的”都不符合语境，故排除。[A]disappointed“失望的”，?符合句义，是正确答案。
