根据下面材料，回答题。 Many people believe the glare from snow causes snow-blin-考呗网题库移动版

单选题 根据下面材料，回答题。
Many people believe the glare from snow causes snow-blindness. Yet, dark glasses or not, they find themselves suffering from headaches and watering eyes, and even snow-blindness, when exposed to several hours of "snow light".
The United States Army has now determined that glare from snow does not cause snow-
blindness in troops in a snow-covered country. Rather, a man's eyes frequently find nothing to focus on in a broad expanse of barren snow-covered terrain. So his gaze continually shifts and jumps back and forth over the entire landscape in search of something to look at. Finding nothing, hour after hour, the eyes never stop searching and the eyeballs become sore and the eye muscles ache. Nature offsets this irritation by producing more and fluid which covers the eyeball. The fluid covers the eyeball in increasing quantity until vision blurs, then is observed, and the result is total, even though temporary, snow-blindness.
Experiments led the Army to a simple method of overcoming this problem. Scouts ahead of a main body of troops are trained to shake snow from evergreen bushes, creating a dotted line as they cross completely snow-covered landscape. Even the scouts themselves throw lightweight, dark colored objects ahead on which they too can focus. The men following can then see something.
Their gaze is arrested. Their eyes focus on a bush and having found something to see, stop scouring the snow-blanketed landscape. By focusing their attention on one object at a time, the men can cross the snow without becoming hopelessly snow-blind or lost. In this way the problem of crossing a solid white terrain is overcome.
To prevent headaches, watering eyes and blindness caused by the glare from snow, dark glasses are__________.

A．indispensible
B．useful
C．ineffective
D．available

参考答案C

解析: 根据第一段“Yet，dark glasses or not，theyfindthemselves sufferingfrom headaches and watering eyes，and even snow-blindness”可知，深色眼镜并不起作用，故选C。

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单选题 When the eyes are sore, tears are produced to__________.

A．clear the vision
B．remedy snow-blindness
C．ease the irritation
D．loosen the muscles

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单选题 Snow-blindness may be avoided by__________.

A．concentrating to the solid white terrain
B．searching for something to look at in snow-covered terrain
C．providing the eyes with something to focus on
D．covering the eyeballs with fluid

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单选题 The scouts shake snow from evergreen bushes in order to__________.

A．give the men behind something to see
B．beautify the landscape
C．warm themselves in the cold
D．prevent the men behind from losing their way

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