单选题
Death comes quickly in the mountains. Winter holiday
makers are caught unaware as they happily ski away from the fixed runs, little
realizing that a small avalanche (雪崩) can send them crashing in a bone breaking
fall down the slope and leave them buried under tons of white snow. There are
lots of theories about how to avoid disaster when hit by an avalanche. Practice
is normally less cheerful. The snow in the Salzburg of Austria
where a recent disaster took place was typical avalanche material. For several
days before the incident I had skied locally. Early winter snow was wearing thin
and covered with ice. On top of that new, warmer flakes (雪片) were gently falling
to produce a dangerous carpet. To the skier who enjoys unmarked slopes it is
tempting stuff, deep new powder snow on a hard base—the skiing that dreams are
made of. And sometimes nightmares. Snow falls in sections like
a cake. Different sections will have different densities because of the
temperatures at the time of the fall and in the weeks afterwards. Problems come
when any particular section is too thick and not sticking to the section
beneath. The snow of the past few weeks had been falling in rather higher
temperatures than those of December and early January. The result of these
conditions is that even a light increase in the temperature sends a thin stream
of water between the new snow and the old. Then the new snow simply slides off
the mountain. Such slides are not unexpected. Local citizens
know the slopes which tend to avalanche and the weather in which such slides are
like. Traps are Set to catch the snow or prevent it slipping; bombs are placed
and exploded from time to time to set off small avalanches before a big one has
time to build up; and, above all, skiers are warned not to ski in dangerous
areas. In spite of this, avalanches happen in unexpected areas
and, of course, skiers ignore, the warnings. The one comfort to recreational
skiers, however, is that avalanche incidents on the, marked ski-slopes are
quite rare. No ski area wants the image of being a death trap.
单选题
Winter holiday makers in the mountains come face to face with death
because______.
A. they fail to realize how dangerous avalanches can be
B. they are not expert enough at skiing on the fixed runs
C. they are trying to avoid areas where avalanches happen
D. they ski great distances down the mountainsides