Avalanches(雪崩)areoneofthosenaturaldisastersthatcancaus...

问题详情：

 Avalanches (雪崩) are one of those natural disasters that can cause great damage and only Mother Nature knows when and where they are going to occur. Even with modern technology it is still impossible to know exactly when or where one is going to occur. Mountain climbers are wise to be careful, as avalanches kill many of them each year.

    The physics of how and why an avalanche occurs is complex. There are times of higher probability. During the year, the transition（转变）from winter to spring will cause some snow and ice to melt, which may trigger(引起) avalanches. Also at daybreak there is a higher probability due to the temperature change.

    While climbers hike up slopes, some distance between the climbers should be kept. If an avalanche occurs, then there will be fewer lives lost and a higher probability that someone will be able to seek help. Since an accident is more likely to happen when a top layer of snow is loose, avoid areas where heavy snow or rain has recently occurred.

    Try to choose areas that you are familiar with and stay in areas with rocks, bushes and trees. Trees and bushes allow snow to pile up and keep the layers stable. If an avalanche occurs, trees will take the impact of the snow, so there is a better chance of being safe.

    Climbers must pay attention to the degree of the slope. Avalanches won’t occur on level ground and there is little snowfall on very steep areas. The greatest danger is in areas where the slope is between 25 and 40 degrees.

    Remember that, if you get stuck in an avalanche, there is no car hire available to take you to the nearest airport.

5. What do we know from the first paragraph?

A. Many mountain climbers die of avalanches each year.

B. Of all the natural disasters, avalanches cause the greatest damage.

C. Most climbers who meet avalanches die for not paying enough attention to avalanches.

D. With the development of science and technology, avalanches can now be predicted exactly.

6. Why is there a higher probability that an avalanche occurs at daybreak?

A. Because daybreak is the coldest time of the day in the mountain.

B. Because it often snows heavily in the mountains at daybreak.

C. Because temperature changes at daybreak.

D. Because the top layer snow is loose at daybreak.

7. It wouldn’t be a good idea for a climber to _______ while climbing a mountain.

A. Keep some distance from other climbers

B. Avoid areas where heavy snow or rain has recently occurred.

C. Choose areas that he or she is familiar with

D. Climb up a slope which is between 25 and 40 degrees

【回答】

ACD

知识点：科普环保类阅读

题型：阅读理解