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　　2015年職稱英語考試理工類完形填空二級文章(1)

　　Avalanche and Its Safety

　　An avalanche is a sudden and rapid flow of snow, often mixed with air and water, down a mountainside. Avalanches are among 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 that supports it. Determining the critical load, the amount of over-burden which is likely to cause an avalanche, 　　is 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 risk of avalanche. Snow does not gather significantly on steep slopes; also, snow does not flow easily on flat slopes. Human-triggered avalanches have the greatest incidence when the snow's angle of rest is between 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 flat 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 use; 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 is never 100% safe. Good avalanche safety is a continuous process, including route selection and examination of the snowpack, weather conditions, and human factors. Several well-known good habits can also reduce the risk. If local authorities issue avalanche risk reports, they should be considered and all warnings should be paid attention 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 missing or damaged. Avoid traveling below others who might trigger an avalanche.

　　雪崩和安全問題

　　雪崩是雪摻雜著空氣和水沿著山體突然迅猛地滑動造成的。雪崩是造成山區(qū)人們生命和財產安全的最大危險之一。

　　所有雪崩都是由于物質的過渡負荷造成，通常是積雪堆積過厚，很不穩(wěn)固，超出了山坡面的承載能力。要確定山坡的臨界承載量，可能造成突然雪崩的負荷量是一項很復雜的任務，需要衡量多個因素。

　　通常傾斜度小于25度，大于60度的山坡發(fā)生雪崩的可能性要小一些。積雪不會在陡峭的山坡上大量堆積，同樣也不會在平緩的山坡上快速滑動。當雪在靜止狀態(tài)下的角度在35-45度之間，最可能發(fā)生人為觸發(fā)的雪崩。人為引發(fā)雪崩的臨界角度是38度，是最易人為引發(fā)雪崩的角度。常規(guī)經驗是：一個平緩的足以堆積積雪，同時陡峭的適合人們滑雪的山坡，無論角度如何，都有可能產生雪崩。此外，雪崩的危險隨著使用的增加而增加，換言之，滑雪者活動得越頻繁，雪崩的可能性越大。

　　由于雪崩研究的復雜性，冬天在人煙稀少的地區(qū)旅行從來不是百分之百的安全。很好地躲避雪崩，保持安全是一個連續(xù)的過程，包括選擇路線、檢查積雪、了解天氣狀況及其他人為因素。以下幾個廣為人知的好習慣也可以降低風險：如果當地權威部門發(fā)布了雪崩警報，你應當予以考慮，加以注意。絕不要不加審度，就立刻接受他人意見。積雪自形成的那時就幾乎注定要發(fā)生變化。認真觀察地形，注意明顯的雪崩路徑：沒有植物或植物被毀壞的地方。不要在那些可能引發(fā)雪崩的人或事物下面行走。