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 (少植被的) snow-covered terrain (地形). 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 eases this irritation by producing more fluid which covers the eyeball. The fluid covers the eyeball in increasing quantity until vision blurs (模糊), then is obscured (遮蔽), 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.
小题1:To prevent headaches, watering eyes and blindness caused by the glare from snow, dark
glasses are _________.
A．indispensable and essential
B．useful
C．ineffective
D．available小题2:When the eyes are sore tears are produced to _________.
A．balance the pain
B．treat snow-blindness
C．clear the vision
D．loosen the muscles小题3:Snow-blindness may be avoided by _________.
A．concentrating on 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 more fluid小题4:The scouts shake snow from evergreen bushes in order to _________.
A．prevent the men behind losing their way
B．beautify the landscape of the terrain
C．warm themselves in the severe cold
D．give the men behind something to see小题5:A suitable title for this passage would be _________.
A．nature's cure for snow-blindness
B．snow-blindness and how to overcome it
C．soldiers marching in the snow
D．snow vision and its effect on eyesight
小题1:C
小题2:A
小题3:C
小题4:D
小题5:B
题目分析：本文讲述雪盲，及出现的原因与克服的方法
小题1:C细节理解题。根据第一段提到they find themselves suffering from headaches and watering eyes, and even snow-blindness, when exposed to several hours of “snow light”.戴不戴眼镜都会产生“雪盲”的症状，如头疼，流泪甚至雪盲，故选C项。
小题2:A细节理解题。根据第二段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此时泪水流出来充满眼眶，眼睛看不清，导致雪盲
小题3:C细节理解题。根据第二段提到的侦察兵的做法告诉我们，雪盲的产生是因为在雪地里眼睛找不到具体目标，由于寻找不到看的物体才产生雪盲。人们就将灌木上的雪去掉，扔一些深色物体，其目的是C项。
小题4:D细节理解题。根据第二段提到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.可知目的是给一些背景给他们看，故选D项。
小题5:B 主旨大意。本文讲述雪盲，及出现的原因与克服的方法，故选B项。