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.

　　詞匯：

　　avalanche / ?v?l?nt?, -lɑ?n? / n.雪崩

　　snowpack / sn??p?k / n.積雪場

　　terrain / tere?n / n.地形，地勢

　　steep / sti?p / adj.險峻的，陸峭的

　　trigger / tr?g? / v.引起，激發

　　incidence / ?ns?d?ns / n.發生

　　ski / ski? / v.滑雪

　　complexity / k?mpleks?t? / n.復雜性

　　注釋：

　　1.angle of rest：這里指積雪保持靜止的角度。

　　2.rule of thumb：指a broadly accurate principle, based on experience or practice rather than theory，即通用法則，經驗法則

　　3.Additionally：是一個副詞，用來引人新的事實或論點，意為此外。

　　4.backcountry：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

　　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.

　　詞匯：

　　avalanche / ?v?l?nt?, -lɑ?n? / n.雪崩

　　snowpack / sn??p?k / n.積雪場

　　terrain / tere?n / n.地形，地勢

　　steep / sti?p / adj.險峻的，陸峭的

　　trigger / tr?g? / v.引起，激發

　　incidence / ?ns?d?ns / n.發生

　　ski / ski? / v.滑雪

　　complexity / k?mpleks?t? / n.復雜性

　　注釋：

　　1.angle of rest：這里指積雪保持靜止的角度。

　　2.rule of thumb：指a broadly accurate principle, based on experience or practice rather than theory，即通用法則，經驗法則

　　3.Additionally：是一個副詞，用來引人新的事實或論點，意為此外。

　　4.backcountry：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