填空题

Many people believe the glare from snow causes snow blindness. However, the U.S. Army has now (36) 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 (37) of barren snow-covered terrain. So his gaze continually (38) and jumps back and forth over the entire landscape in search of something to look at. Finding nothing, the eyes never stop searching and the eyeballs become (39) and the eye muscles ache. Nature (40) this irritation by producing more fluid which covers the eyeball. The fluid covers the eyeball in (41) quantity until vision blurs, then is (42) , and the result is 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 (43) on which they too can focus. The men following can then see something. Their gaze is (44) . 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 (45) . In this way the problem of crossing a solid white terrain is overcome.
A．landscape I．defined
B．lost J．shifts
C．blurred K．obscured
D．increasing L．expanse
E．surveyed M．offsets
F．away N．ahead
G．determined O．sore
H．arrested