（一）AvalancheandItsSafety根据下列材料，请回答下列问题。Anavalancheisasuddenandrapidflowofsn

共享题干题                                              （一）Avalanche and Its Safety根据下列材料，请回答下列问题。    An avalanche is a sudden and rapid flow of snow, often mixed with air and water, down a mountainside. Avalanches are_________ (51) the biggest dangers in the mountains for both life and property.    All avalanches are caused by an over-burden of material, typically snowpack, that is too massive and unstable for the slope _________ (52) supports it. Determining the critical load, the amount of over-burden which is _________ (53) to cause an avalanche,_________ (54) a plex task involving the evaluation of a number of factors.    Terrain slopes flatter than 25 degrees or steeper than 60 degrees typically have a low _________(55) of avalanche. Snow does not _________ (56) significantly on steep slopes ; also, snow does not_________ (57) easily on fiat slopes. Human-triggered avalanches have the greatest incidence when the snow's angle of rest is _________ (58) 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 is: A slope that is _________(59) 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_________(60) ; that is, the more a slope is disturbed by skiers, the more likely it is that an avalanche will occur.    Due to the plexity of the subject, winter travelling in the backcountry is never 100% safe. Good avalanche safety is a continuous_________ (61) , including route selection and examination of the snowpack, weather _________ (62) , and human factors. Several well-known good habits can also _________(63) the risk. If local authorities issue avalanche risk reports, they should be considered and all warnings should be paid _________(64) 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_________(65) or damaged. Avoid travelling below others who might trigger an avalanche.1.[不定向选择题]_________A.fall B.flow C.roll D.gather 2.[不定向选择题]_________A.when B.that C.who D.whose