Directions: After reading the passage below, fill in the blanks to make the passage coherent and grammatically correct. For the blanks with a given word, fill in each blank with the proper form of the given word; for the other blanks, use one word that best fits each blank.
How Do Avalanches Happen
If you’re ever skiing in the mountains, you’ll want to be aware of avalanches. An avalanche is a sudden flow of snow down a slope, such as a mountain. The amount of snow in an avalanche 【小题1】 (vary) based on many things, but it can be such a huge amount that it can bury the bottom of a slope in dozens of feet of snow.
Avalanches 【小题2】 be caused by natural things. For example, new snow or rain can cause built-up snow to loosen and fall down the side of a mountain. Artificial triggers（诱发因素）can also cause avalanches. For example, snowmobiles, skiers, and explosives 【小题3】 (know) to lead to avalanches.
Avalanches usually occur during the winter and spring, 【小题4】 snowfall is greatest. As they are dangerous to any living beings in their path, avalanches have destroyed forests, roads, railroads and even entire towns. Warning signs exist that allow experts to predict -- and often prevent -- avalanches from 【小题5】
(occur). When over a foot of fresh snow falls, experts know to be on the lookout for avalanches. Explosives can be used in places 【小题6】 massive snow buildups to trigger much smaller avalanches that don’t pose a danger to persons or property.
When deadly avalanches do occur, the moving snow can quickly reach over 80 miles per hour. Skiers caught in such avalanches can be buried under dozens of feet of snow. 【小题7】 it’s possible to dig out of such avalanches, not all are able to escape.
If you get tossed about by an avalanche and find yourself 【小题8】 (bury) under many feet of snow, you might not have a true sense of which way is up and which way is down. Some avalanche victims have tried to dig their way out, only to find that they were upside down and digging 【小题9】 farther under the snow rather than to the top!
Experts suggest that people caught in an avalanche try to dig around you 【小题10】 (create) a space for air, so you can breathe more easily. Then, do your best to figure out which way is up and dig in that direction to reach the surface and signal rescuers.
