填空题. A．certainly B．render C．replies D．breezes E．involuntary F．coming from G．affected H．people I．hearing J．obviously K．snores L．feeling M．responses N．coming into O．exhaling An unidentified wit once said, "Laugh, and the world laughs with you. Snore, and you sleep alone." Yet snoring is far from a laughing matter as those unfortunates with good 21 , who are rightly subjected to the sounds of the snoring disorder, will testify. It has been estimated that one of eight Americans 22 ; this means that there are approximately 21 million people—women as well as men—who 23 an unpleasant sound when they are asleep. And assuming that each snorer disturbs the sleep of at least one other person, it 24 follows that there are 21 million unhappy listeners. While a sleeping person breathes, either in or out, several structures in his nose and throat generate the snoring. The sounds, 25 the soft palate and other soft structures of the throat, are caused by vibratory 26 to inflowing and out flowing air. When the soft tissues of the mouth and throat come close to the lining of the throat, the vibrations that occur are caused by the position of the tongue. In short, the noise made by snoring can be compared to the noise when 27 flutter a flag on a pole, The frequency of the vibrations depends on the size, density, and elasticity of the 28 tissues and on the force of the air flow. Although it is usually the process of inhaling or 29 through the mouth that cause snoring, short snores come from the nose of an open-mouthed sleeper. In all fairness to snorers, however, it should be emphasized that snoring is an 30 action which stops as the offender is awakened.