39.
What does the “Wheelchair Access” probably mean?
A. It’s a kind of
sidewalk built for disabled people.
B. It’s an entrance to a
house built for the disabled people.
C. It’s a street built
for the disabled people to have a walk.
D. It’s a special path
for the disabled people to get to the garage.
(B)
Many people believe the
glare from snow causes snow blindness. Yet, with 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 often find nothing
to focus on in a broad space of snow-covered without-grass land. So his gaze continually
moves and jumps back and forth over the entire landscape in search of something
to look
at. Finding something, hour after hour, the eyes never stop searching and the
eyeballs become tired and the eye muscles ache. Nature makes up for this discomfort
by producing more and more fluid (液体) which covers the eyeball. The fluid covers the eyeball in increasing
quantity until it makes eyes difficult to see clearly, and the result is total,
even though for a short time, snow blindness.
Experiments lead the Army to a
simple method of overcoming this problem. Scouts (侦察员) ahead of the 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 can focus too. The
men following can then see something. Their gaze is arrested. Their eyes focus on a bush
and having found something to see, stop searching 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 continuous white land
is overcome.