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____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 it. Determining the critical load, the amount of over-burden which is____3____ cause an avalanche, ____4____ acomplex task involving the evaluation of a number of factors.
Terrain slopes flatter than25degrees or steeper than60degrees 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 avalanches have the greatest incidence when the snows angle of rest1 is____8____ 35 and45 degrees; the critical angle, the angle at which the human incidence of avalanches is greatest, is38degrees. The 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 angle. Additionally3, avalanche risk increases with ____10____;that is, the more a slope is disturbed by skiers, die more lijkely it is that an avalanche will occur.
Due to the complexity of the subject, winter travelling in the backcountry4 is never 100% safe. Good avalanche safety is a continuous____11____,, including route selection and examination of the snowpack, weather____12____ and human factors. Several well-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.
词汇：
avalanche / ?v?l?nt?, -lɑ?n? / n.雪崩
snowpack / sn??p?k / n.积雪场
terrain / tere?n / n.地形，地势
steep / sti?p / adj.险峻的，陆峭的
trigger / tr?g? / v.引起，激发
incidence / ?ns?d?ns / n.发生
ski / ski? / v.滑雪
complexity / k?mpleks?t? / n.复杂性
注释：
1.angle of rest：这里指积雪保持静止的角度。
2.rule of thumb：指a broadly accurate principle, based on experience or practice rather than theory，即通用法则，经验法则
3.Additionally：是一个副词，用来引人新的事实或论点，意为此外。
4.backcountry：人烟稀少的地区
练习：
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