英语2011上学期期末试题

江西财经大学现代经济管理学院

2011-2012第一学期期末考试试卷

Part II Reading Comprehension (Skimming and Scanning) （10%）Directions:

For questions 1-7, mark

Y (for YES) if the statement agrees with the information given in the passage;

N (for NO) if the statement contradicts the information given in the passage;

NG (for NOT GIVEN) if the information is not given in the passage.

For questions 8-10, complete the sentences with the information given in the passage.

Wildfires

In just seconds, a spark or even the sun’s heat alone sets off an extremely large fire. The wildfire quickly spreads, consuming the thick, dried-out plants and almost everything else in its path. What was once a forest becomes a virtual powder keg of untapped fuel. In a seemingly instantaneous burst, the wildfire overtakes thousands of acres of surrounding land , threatening the homes and lives of many in the vicinity. Fire Starters . On a hot summer day , when drought conditions peak , something as small as a spark from a train car’s wheel striking the track can ignite a raging wildfire. Sometimes, fires occur naturally, ignited by heat from the sun or a lightning strike . However, the majority of wildfires are the result of human carelessness. Common causes for wildfires include: Arson(故意)放火，纵火. Campfires

Discarding lit cigarettes. Improperly burning debris Playing with matches or fireworks

Prescribed fires - Everything has a temperature at which it will burst into flames. This temperature is called a material’s flash point. Woods flash point is 572 degrees Fahrenheit (300 ) . When wood is heated to this temperature, it releases hydrocarbon gases that mix with oxygen in the air, combust and create fire.

There are three components needed for ignition and combustion to occur. A fire requires fuel to burn, air to supply oxygen, and a heat source to bring the fuel up to ignition temperature. Heat, oxygen and fuel form the fire triangle. Firefighters often talk about the fire triangle when they are trying to put out a blaze. The idea is that if they can take away any one of the pillars of the triangle,

they can control and ultimately extinguish the fire. After combustion occurs and a fire begins to burn, there are several factors that determine how the fire spreads. These three factors include fuel, weather and topography. Depending on these factors, a fire can quickly fizzle or turn into a raging blaze that scorches thousands of acres. Fueling the Flames Wildfires spread based on the type and quantity of fuel that surrounds it. Fuel can include everything from trees, underbrush and dry grassy fields to homes. The amount of flammable material that surrounds a fire is referred to as the fuel load. Fuel load is measured by the amount of available fuel per unit area, usually tons per acre .

A small fuel load will cause a fire to burn and spread, with a low intensity. If there a lot of fuel, the fire will burn more intensely, causing it to spread faster. The faster it heats up the material around it, the faster those materials can ignite. The dryness of the fuel can also affect the behavior of the fire. When the fuel is very dry, it is consumed much faster and creates a fire that is much more difficult to contain. Here are the basic fuel characteristics that decide how it affects a fire: Size and shape Arrangement

Moisture content Small fuel materials , also called flashy fuels , such as dry grass , pine needles , dry leaves, twigs and other dead brush , burn faster than large logs or stumps (this is why you start a fire with kindling rather than logs). On a chemical level, different fuel materials take longer to ignite than others. But in a wildfire, where most of the fuel is made of the same sort of material, the main variable in ignition time is the ratio of the fuel’s total surface area to its volume. Since a twig’s surface area is much larger than its volume, it ignites quickly. By comparison, a tree’s surface area is much smaller than its volume, so it needs more time /to heat up before it ignites. As the fire progresses, it dries out the material just beyond it. Heat and smoke approaching potential fuel causes the fuel’s moisture to evaporate. This makes the fuel easier to ignite when the fire finally reaches it. Fuels that are somewhat spaced out will also dry out faster than fuels that are packed tightly together, because more oxygen is available to the thinned-out fuel. More tightly-packed fuels also retain more moisture, which absorbs the fire’s heat. Wind and Rain - .Weather plays a major role in the birth, growth and death of a wildfire. Drought leads to extremely favorable conditions for wildfires, and winds aid a wildfire’s progress. Weather can spur the fire to move faster and engulf more land. It can also make the job of fighting the fire even more difficult. There are three weather ingredients that can affect wildfires: Temperature

Wind , Moisture

As mentioned before, temperature has a direct effect on the sparking of wildfires, because heat is one of the three pillars of the fire triangle. The sticks, trees and underbrush on the ground receive radiant heat from the sun, which heats and dries potential fuels. Warmer temperatures allow for fuels to ignite and burn faster, adding to the rate at which a wildfire spreads. For this reason, wildfires tend to rage in the afternoon, when temperatures are at their hottest . Wind probably has the biggest impact on a wildfire’s behavior. It’s also the most unpredictable