Many people believe the glare from snow causes snowblindnenss. Yet, dark glasses or not , they find themselves suffering from headaches and watering eyes,and even snowblindness,when exposed to several hours of snow light .
The United States Army has now determined that glare from snow does not cause snowblindness in troops in a snow-covered country.Rather, a mans eyes frequently find nothing to foucs 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 tsomething to look at. Finding nothing, hour after hour, the eyes never sotp 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 coversthe eyeball in increasing quantity until vision blurs, then is obsured,and the result is total, even though temporary,snowblindness.
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 lanscape. By focusing their attention on one object at a time,the men can cross the snow without becoming hopelessly snowblind or lost. In this way the problem of crossing a solid white terrain is overcome.
1.To prevent headaches, watering eyes and blindness caused by the glare from snow, dark glasses are_____.
A.indispensible
B.useful
C.ineffective
D.available
2.When the eyes are sore tears are produced to ________.
A.clear the vision
B.remedy snowblindness
C.ease the irritation
D.loosen the muscles
3.Snowblindness 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 foucs on
D.covering the eyeballs with fluid
4.The scouts shake snow from evergreen bushes in order to _______.
A.bive 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
5.A suitable title for this passage would be _______.
A.snowblindness and how to overcome it
B.natrues cure for snowblindness
C.soldiers in the snow
D.snow vision
答案:CCCAA
外研版一年级英语上册教案Unit1 Hello
沪教牛津版小学英语一年级上册 Unit 3 第二课时教案
一年级英语上册Unit8 Playtime 第三课时教案
一年级英语Module1 unit6 Mid-Autumn Festival教案
沪教版小学英语一年级下册教案unit1课时4
一年级英语上册Unit1 My classroom第三课时教案
上海牛津版一年级英语下册Unit9 Revision第二课时教案
牛津版一年级英语上册unit5 Fruit教案(2)
牛津版一年级英语上册unit5 Fruit教案(1)
上海牛津版一年级英语下册Unit2 Small animals教案
苏教版小学一年级英语下册Unit5 On the road教案
上海牛津版一年级英语Unit7 My family教案
牛津小学一年级英语Unit5 Fruit教案(五个课时)
沪教牛津版一年级英语上册教案Unit1 My classroom第二课时
沪教版小学英语一年级下册教案unit1课时2
一年级英语下册Unit2 Small animals教案2
一年级英语上册教案Unit1 My classroom第一课时教案
新课标小学英语第一册期末考试百词范围
沪教版小学英语一年级下册教案unit1单元分析
新起点小学一年级英语下册Unit11 Toys教案
沪教牛津版小学英语一年级上册 Unit 8 教案
苏教版牛津小学一年级英语教案Unit1 What`s your name
牛津版小学一年级英语上册Unit1 Hello教案
上海版牛津一年级英语教案Unit8 Playtime(总五课时)
一年级英语上册教案 Unit1My classroom 第三课时
一年级英语教案Module1 unit6 Mid-Autumn Festival
一年级英语上册教案 Unit 1 第二课时
上海牛津版一年级英语下册Unit2 Small animals第五课时教案
一年级英语上册教案 Unit 1 Period 1
牛津版一年级英语上册unit5 Fruit教案(3)
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |