The preventive measures for forest fires include some preemptive(抢先)methods that can help reduce the risks of fires and control their severity and spread，and thus, maintain ecological balance and protect resources．Close monitoring of forest fires caused by natural factors can help prevent their spread to a large extent．To contain forest fires，fire departments usually use water and chemical fire retardants(抑制剂)that can be dropped from planes and helicopters．To control the spread of a wildfire．firefighters usually create a control line by removing all fuel from an area so that the fire cannot travel across it．
Controlled burns are often employed by government authorities to reduce fuel buildup，and clean up the fallen leaves，and thus，prevent the spread of forest fires to a vast area．Regular controlled burns can also help maintain biodiversity(生物多样性)，as the smoke and heat produced in the process can facilitate(促进)the growth of seeds of certain plant species．Apart from these，responsible human behavior can help reduce the number of forest fires to a great extent．In fact，we can reduce the number of wildfires dramatically by not leaving behind any source of fire in the forest.
Forest fires can affect climate and weather to a great extent，besides causing severe damage to valuable trees．Wildfires can increase the level of greenhouse gases(water vapor, carbon dioxide，etc)，and therefore increase pollution and global warming．However, they are also an important part of the ecosystem，and many plants depend on the heat and smoke generated by wildfires for their growth and reproduction．But large wildfires can cause extensive damage to the ecosystem，which again highlights the importance of effective control and prevention of forest fires·
小题1:What may be the best title for this passage?
A．Control and Prevention of Forest Fires
B．How to Keep Ecological Balance
C．Effects of Forest Fires
D．Methods of Fire Spread Control小题2:Firefighters get rid of all fuel in all area in order to ____________．
A．keep close monitoring of forest fires
B．prevent the forest fire from occurring
C．protect the animals there
D．stop the wildfire from spreading小题3:The government arranges some controlled burns to_______________．
A．burn the rubbish and keep the forest clean
B．help keep ecological balance of nature
C．reduce fuel buildup and limit forest fires spread
D．provide reasonable conditions for some plants’growth小题4:A controlled forest fire may play a positive role because ________________.
A．a new forest will appear soon
B．it promotes the development of some seeds
C．nature keeps its balance only by wildfires
D．it makes the trees grow faster than before小题5:The last paragraph tells us that _______________．
A．the greenhouse gases are caused mainly by wildfires
B．wildfires have both positive and negative effects
C．people should be aware of the necessity of wildfires
D．all the valuable trees disappear owing to wildfires
