Avalanche and Its Safety
An avalanche is a sudden and rapid flow of snow,often mixed with air and water,down a anches are 1 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 2 supports rmining 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 low5 of does not6 significantly on steep slopes;also,snow does not7 easily on fiat n-triggered avalanches have the greatest incidence when the snow's angle of rest 1is 8 35 and 45 degrees;the critical angle,the angle at which the human incidence of avalanches is greatest,is 38 rule of thumb2 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 tionally3,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 backcountry4 is never 100% avalanche safety is a continuous 11 ,including route selection and examination to the snowpack,weather 12 ,and human ral well-known good habits can also 13 the local authorities issue avalanche risk reports,they should be considered and all warnings should be paid 14 r follow in the tracks of others without your own evaluations;snow conditions are almost certain to have changed since they were rve the terrain and note obvious avalanche paths where plants are 15 or d traveling below others who might trigger an avalanche.
詞彙：
avalanche n.雪崩 trigger v.引起，激發
snowpack n.積雪場 incidence n.發生(率)
terrain n.地形，地勢 ski v.滑雪
steep adj.險峻的，陡峭的 complexity n.複雜性
註釋：
e of rest：這裡指積雪保持靜止的角度。
b：指“a broadly accurate principle，based on experience or practice rather that theory”，即“通用法則，經驗法則”。
tionally：是一個副詞，用來引人新的事實或論點，意為“此外”。
country：人煙稀少的地區。
練習：
1.A among B of C to D in
2.A when B that C who D whose
3.A mostly B likely C clearly D surely
4.A are B will be C is D was
5.A weight B form C risk D work
6.A fall B flow C roll D gather
7.A fall B flow C roll D gather
8.A among B between C with D for
9.A thick B thin C flat D rocky
10.A use B time C snow D rain
11.A journey B trip C fact D process
12.A conditions B reports C forecast D event
13.A increase B reduce C improve D remove
14.A price B effort C attention D money
15.A missing B grown C big D fresh
答案與題解：
1.A表達“雪崩是山上可能發生的最大危險之一”的意思，因此應該選擇among(在……之中)。
2.B從該句的語法結構上來看，此處需要一個關係代詞，代替slope，所以that是最佳選擇。選項A、C、D均不符合語法。
3.B選項A不符合語法，c和D符合語法，但不符合常識：過度的雪的積壓可能導致雪崩，而不是必定導致雪崩。所以，B是最佳答案。
4.C該句的主語是Determining the critical load，從上下文來看應該使用一般現在時，所以C是正確答案。
5.C要確定本題答案的一個有效的方法是排除法。a.10w weight/form work of avalanche都不合邏輯，只有a low risk of avalanche符合上下文的意思。下面的句子解釋了low risk of avalanche的道理，更證實了選risk是正確的。
6.D第6和第7題可以一起考慮。整個句子的意思是：在坡度大的'坡上，雪不會大量堆積。
在較為平坦的坡面，雪不會輕易滑動。
7.B(見6)
8.B理解了句子的意思就不難判斷選項：雪在靜止狀態下，角度在35_45度之間，最可能發生人為觸發的雪崩。between：在……之間。
9.C這個句子說明的是什麼樣的山坡最易發生雪崩，即，A slope that is flat enough to hold snow but steep enough to 在此做“平坦”解，與後面的steep形成反義。
10.A句中的that is表明，後半部分是對前半部分的進一步說明。所以，這裡的選擇要根據下文的意思判斷。use是最佳選擇，整個句子的意思是：山坡被滑雪者使用的越多，雪崩就越可能發生。 、
11.D儘管選項A、B和D都能和continuous搭配，從全段的內容判斷，只有process是最佳選擇，因為該段描寫的是如何防備雪崩，及如何做好安全措施等一系列問題。
12.A選項A、B、c都可以與weather搭配，但是根據上下文，只有A最為符合文章的內容。
13.B選項A不符合句子的意思;c不能和risk搭配;D也不符合句子的意思，因為不可能完全消除雪崩的隱患。
14.C該句主句使用的是被動語態，第二個動詞是pay attention t0的被動形式。l選項A、B、D均不符合句子的意思。
15.A該句是作者給出的一系列忠告之一，即，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。選項8、C、D均不符合句義。
