18． it can be inferred from the passage that the author’s explanation in lines 50－54 would be most weakened if which one of the following were true？
　　属于逻辑题中的反对题
　　musicians who perform in modern orchestras generally receive more extensive training than did their nineteenth－century counterparts．
　　breaks between the movements of symphonies performed during the early nineteenth century often lasted longer than they do today because nineteenth－century musicians needed to retune their instruments between each movement．
　　early nineteenth－century orchestral musicians were generally as concerned with the audience’s response to their music as are the musicians who perform today in modern orchestras．
　　early nineteenth－century audience applauded only perfunctorily after the first three movements of symphonies and conventionally withheld their most enthusiastic applause until the final movement was completed．
　　直接否定，抬杠法
　　early nineteenth－century audiences were generally more knowledgeable about music than are their modern counterparts．
　　19． it can be inferred from the passage that the author would be most likely to agree with which one of the following assertions regarding the early music recordings mentioned in the third paragraph？
　　属于信息题（中的可定位信息题）
　　these recordings fail to recognize that the last movements of haydn’s and mozart’s symphonies were often played slower in the eighteenth century than they are played today．
　　跨区型错误
　　these recordings betray the influence of baroque musical style on those early music advocates who have recently turned their attention to the music of haydn and mozart．
　　跨区型错误
　　by making audible the sound of an orchestral piano that was inaudible in eighteenth century performances， these recordings attempt to achieve aesthetic integrity at the expense of historical authenticity．
　　by making audible the sound of an orchestral piano that was inaudible in eighteenth century performances， these recordings unwittingly create music that is unlike what eighteenth century audiences heard．
　　these recordings suggest that at least some advocates of early music recognize that concepts of musical intensity and excitement have changed since haydn and mozart composed their symphonies．
　　“反”型错误
　　20． the author suggests that the modern audience’s tendency to withhold applause until the end of a symphony’s performance is primarily related to which one of the following？
　　the replacement of the orchestral piano as a method of keeping the orchestra together．
　　a gradual increase since the time of mozart and beethoven in audiences’ expectations regarding the ability of orchestral musicians．
　　a change since the early nineteenth century in audiences’ concepts of musical excitement and intensity．
　　a more sophisticated appreciation of the structural integrity of the symphony as a piece of music．