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根据材料，回答题。

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 in Cumbria. _________ （52 ） 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 hkestatic 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 mote 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 failing frequencies to indicate whether people should goup_________ （64） down stairs. They were _________ （65 ） with the aid of a large grant from British

Nuclear Fuels.

回答（51）题 查看材料

A.without

B.with

C.having

D.selling

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