For centuries, canes have served blind and partially sighted people well by giving them a means to negotiate the world around th

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问题     For centuries, canes have served blind and partially sighted people well by giving them a means to negotiate the world around them. The only serious upgrade they have undergone dates back to 1921, when a Briton called James Biggs, who had recently lost his sight, painted his own cane white in order to make it easily visible and to alert others to the presence of someone unable to see nearby obstacles. In the opinion of Daniela Rus of MIT, however, the white cane has had its day. Dr. Rus would like to replace it with a system that scans its user’s environment and communicates back to him what it sees.
    Dr. Rus’s device consists of a camera worn on a string around the neck, and a belt. A computer inside the camera creates a three-dimensional image of the area ahead of the wearer, processes it to extract relevant information, and uses the results to pass on appropriate signals via the belt.
    Dr. Rus knew from previous attempts to build devices of this sort that what might seem the obvious way of manifesting those signals, namely as sounds with specific meanings, was not a good approach. Blind people depend a lot on their hearing and do not like it when stylish devices hamper this sense with beeps and clicks. Hence the belt, which has five vibrating motors installed in it.
    That configuration permits the computer to warn a wearer when he is on a collision course with an obstacle. It does so by telling the motor pointing most closely in the direction of the obstacle to vibrate. If the wearer is walking towards a wall, for example, the central motor vibrates softly when he comes within a couple of metres of it. If he ignores this, perhaps because he actually wants to reach the wall, the computer increases the amplitude as he closes in, giving him a good idea of exactly how far away he is. When compared with white cane, it reduced blind persons’ collisions with others by 86%.
    The new system can do more than just help someone walk around without collisions, for the belt incorporates a touchpad that is inscribed with instructions in Braille. This permits the user to program it to perform specific tasks.
    For example, Dr. Rus knew that blind students often struggle to find an empty seat in a crowded lecture theatre. Adding an appropriate algorithm to the computer’s software helps get around this by enabling it to recognize chairs, and also whether or not a chair is occupied.
    Whether a camera and a belt could replace a cane completely remains to be seen. In particular, Dr. Rus’s system does lack one important feature of Biggs’s innovation. A white cane not only helps a blind person to navigate, it also signals his condition to the rest of the world, allowing others to adjust their behavior accordingly.
Compared with white cane, Dr. Rus’s device can reduce the collision rate by________.

选项 A、a particular profession
B、a vibrating device
C、a three-dimensional image
D、sounds with specific meanings

答案B

解析 细节题。由题干中的Compared with white cane定位到第四段。第四段指出,“计算机会让距离障碍物最近的电动机振动起来。比如,假设用户正在走向一面墙,在距离两三米远时中央电动机就会开始轻微振动,如果他不为所动继续向前——也许是因为他本意就是想走到那栋墙边——计算机会逐渐增加那台电动机振动的幅度,让用户能清楚了解到自己离墙还有多远。”由此可知设备是通过电机振动提醒盲人,从而减少碰撞的可能,故正确答案为B项。A项在文章中并未提及,故排除。三维影像是将信号传入腰带,并不直接提醒用户,故排除C项;D项“有特定含义的声音”在原文第三段中提到,并不利于盲人的听觉,故排除。
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