39. The paragraph following this passage would most likely be about
(A) the cause of hot dry weather.
(B) the various uses of hardwoods.
(C) methods of controlling fires.
(D) the geographical differences between Rocky Mountain Area and the South.

Weather seems to be the most important factor dictating the severity of forest fires. Hot, dry weather lowers the moisture content of fuel. Once a fire has started, wind would become influential concerning oxygen supply and the rate of spread. Other important factors include forest types and forest conditions. For example, fire is more likely to occur in conifers than in hardwoods; slash-covered or brushy areas are especially hazardous because the rate at which combustion consumes fuel is related to fuelvolume or surface area. Some fires are caused by lightening; others are caused by people. Those caused by people may be accidental or intentional. Regional differences exist regarding the causes of fire. For example, fires in Rocky Mountains present a different picture from the fires in the South. 70 percent of the fires in the former area are caused by lightening, whereas intentional fires take up to 40 percent in the later.

天氣似乎是決定森林火災嚴重程度最重要的因素。炎熱乾燥的天氣會降低燃料的含水量。一旦火災發生，風力就會對氧氣供應和火勢蔓延速度產生影響。其他重要因素包括森林類型和森林狀況。例如，針葉林比闊葉林更容易發生火災；枝葉堆積或灌木叢生的區域尤其危險，因為燃燒消耗燃料的速度與燃料體積或表面積有關。有些火災是由閃電引起的；有些則是人為造成的。人為造成的火災可能是意外事故，也可能是人為縱火。火災原因在不同地區有差異。例如，落基山脈的火災情況與南部地區的火災情況截然不同。前者70%的火災是由閃電引起的，而後者人為縱火的比例高達40%。

The paragraph following this passage would most likely be about
(A) the cause of hot dry weather.
(B) the various uses of hardwoods.
(C) methods of controlling fires.
(D) the geographical differences between Rocky Mountain Area and the South.

接下來的段落最有可能討論的是：

(A) 炎熱乾燥天氣的成因。

(B) 硬木的各種用途。

(C) 控制火災的方法。

(D) 洛磯山脈地區與美國南部之間的地理差異。