单选题 Most forest fires are caused by human carelessness, negligence, or ignorance. Forest fire prevention, therefore, is mainly a problem of creating a better understanding of the importance of forests, an awareness of the danger of fire in the woods, and a sense of personal responsibility to safeguard the forests from danger. This is not an easy job. A city dweller, used to paved streets, does not easily change his smoking habits when he goes into the woods.
Careless smokers are responsible for thousands of forest fires each year. Many of these are started when cigarette butts and matches are thrown from automobiles. Others are caused by hunters, hikers, fishermen, or woods workers who are careless in disposing of their smoking materials. The Forest Service has posted rules in many of the National Forests that prohibit smoking except in certain designated areas. Many of the states have laws against throwing lighted materials from automobiles. The prevention of smoker-caused fires, however, depends upon changing the attitudes and behavior of millions of people who smoke in hazardous areas.
The most important natural cause of fire is lightning. This accounts for 11 percent of forest fires on protected land for the entire nation; in the western States, lightning causes a much higher percentage of fires than it does in the East.
Advances in knowledge of fire weather are helping forest protection forces to know when to be alert for lightning-caused fires. Adequate and well-equipped forces can control them quickly and hold the damage to a minimum. Experiments in "seeding" thunder clouds to prevent or control the lightning itself have been in process for many years, but new breakthroughs are needed for any significant reduction in the lightning-caused fires.

单选题 The passage is chiefly about ______.
A. smoking in forests
B. the chief causes of forest fires and their prevention
C. changing the attitudes and behavior of millions of people
D. advances in knowledge of fire weather

单选题 Preventing smoker-caused forest fires is mainly a problem of ______.
A. building the proper knowledge and habits in human beings
B. safeguarding the forests from fire
C. posting rules in forests
D. holding the damage to a minimum

单选题 Lightning-caused fires can be controlled quickly by ______.
A. responsible smokers B. hunters and woods workers
C. adequate and well-equipped forces D. changing people's habits

单选题 Which of the following statements is true?
A. The conservation of forests isn't an easy task.
B. In forests smoking is prohibited in a few safe areas.
C. Lightning, the only natural cause, accounts for 11% of the forest fires in the Western States.
D. New breakthroughs can't be expected from experiments in "seeding" thunder clouds.