题目内容：

Of all nature's disasters, forest fires are often considered the most frightening. Moving at lightning speed, huge walls of flames can burn acres of land in just a few minutes. And although technology, including the use of fire-retardant chemicals, has greatly helped the fight against forest fires, they still do great damage.

According to the National Interagency Fire Center, the fire season last year was the worst on record in terms of the number of fires and acres burned. There were 96. 385 fires and 9.873429 acres affected by fire in a year that was 125% more destructive(毁灭性的) than the10-year average. These fires cost the federal government $1.5 billion to fight, and this figure does not include the money spent by local and state governments as part of the effort.

Fires in the southern states represented half of the national total last year with Texas, Oklahoma and Arkansas being home to a usually high amount of activity. Wildfire has also taken place in Western states such as California, Colorado and Alaska throughout the past 10 years.

It is said that two-thirds of forest fires are started accidentally by people. Almost one quarter are purposely set, while lighting causes 10%.

Forest fires can have advantageous effects. Charcoal(木炭) enriches soil and some plant species(种类) grow well after fire. The cones of the jack pine tree, for example, will not spread their seeds unless there is heat. Douglas fir trees grow best in open sunlight areas after fire.

1.Forest fires are considered to be the most frightening because____.

A. fire-retardant chemicals can't be made use of

B. huge walls of flames can burn acres of land

C. they make the greatest loss of all disasters

D. they spread too fast and do great damage

2.Almost 25% forest fires are set_____.

A. unexpectedly    B. by lighting    C. on purpose    D. naturally

3.What does the last paragraph mainly talk about?

A. The advantages of forest fires.    B. The usage of charcoals.

C. Pine trees need fires.    D. Fires destroy all plants but two.