题目内容：
根据以下材料，回答题Avalanche (雪崩) and Its Safety
An avalanche is a sudden and rapid flow of snow, often mixed with air and water, down a mountainside. Avalanches are__________ (1) the biggest dangers in the mountains for both life and property.
All avalanches are caused by an overburden of material, typically snowpack (积雪场), that is too massive and trustable for the slope__________(2) supports it. Determining the critical load,the amount of over-burden which is __________ (3) to cause an avalanche, __________ (4) a complex task involving the evaluation of a number of factors.
Terrain slopes flatter than 25 degrees or steeper than 60 degrees typically have a low __________(5) of avalanche. Snow does not __________(6) significantly on steep slopes; also, snow does not__________(7) easily on flat slopes. Human-triggered (激发) avalanches have the greatest incidence(发生率) when the snow's angle of rest is __________(8) 35 and 45 degrees; the critical angle, the angle at which the human incidence of avalanches is greatest, is 38 degrees. The rule of thumb (经验法则) is: A slope that is__________(9) enough to hold snow but steep enough to ski has the potential to generate an avalanche, regardless of the angle. Additionally, avalanche risk increases with__________ (10); that is, the more a slope is disturbed by skiers, the more likely it is that an avalanche will occur.
Due to the complexity of the subject, winter travelling in the backcountry (人烟稀少的地区)is never 100% safe. Good avalanche safety is a continuous__________(11), including route selection and examination to the snowpack, weather __________ (12), and human factors. Several we|l-known good habits can also __________ (13)the risk. If local authorities issue avalanche risk reports, they should be considered and all warnings should be paid__________(14) to. Never follow in the tracks of others without your own evaluations; snow conditions are almost certain to have changed since they were made. Observe the terrain and note obvious avalanche paths where plants are__________ (15) or damaged. Avoid traveling below others who might trigger an avalanche.
回答(1)题 A．among
B．of
C．to
D．in
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