[填空题] Although there are many skillful Braille readers, thousands of other blind people find it difficult to learn that system. They are thereby shut (61)______ from the world of books and newspapers, having to (62)______ on friends to read aloud to them. A young scientist named Raymond Kurzweil has now designed a computer which is a major (63)______ in providing aid to the (64)______ . His machine, Cyclops, has a camera that (65)______ any page, interprets the print into sounds, and then delivers them orally in a robot-like (66)______ through a speaker. By pressing the appropriate buttons (67)______ Cyclops’’s keyboard, a blind person can "read" any (68)______ document in the English language. This remarkable invention represents a tremendous (69)______ forward in the education of the handicapped. At present, Cyclops costs $50,000. (70)______ , Mr. Kurzweil and his associates are preparing a smaller (71)______ improved version that will sell (72)______ less than half that pric
A. A．but
B．than
C．or
D．then