共用题干 Singing Alarms Could Save the Blind.If you cannot see,you may not be able to find your way out of a burning building-and that could be fatal .A company in Leeds could change all that______(51)directional sound alarms capable of guiding you to the exit.Sound Alert,a company______(52)the University of Leeds,is installing the alarms in a residential home for______(53)people in Sommerset and a resource centre for the blind inCumbria.______(54)produce a wide range of frequencies that enable the brain to determine where the______(55)is coming from.Deborah Withington of Sound Alert says that the alarms use most of the frequencies that can be______(56)by humans."It is a burst of white noise ______(57)people say sounds like static on the radio,"she says."Its life-saving potential is great."She conducted an experiment in which people were filmed by thermal-imaging cameras trying to find their way out of a large______(58)room. It______(59)them nearly four minutes to find the door______(60)a sound alarm,but only 15 seconds with one.Withington studies how the brain______(61)sounds at the university. She says that the _______(62)of a wide band of frequencies can be pinpointed more easily than the source of a narrow band .Alarms______(63)the same concept have already been installed on emergency vehicles.The alarms will also include rising or falling frequencies to indicate whether people should go up______(64)down stairs.They were______(65)with the aid of a large grant from British Nuclear Fuels. 51._________
A.without B.with C.having D.selling正确答案B
