Read the following passage carefully and then choose the best option to fit each space by circling the letter A, B, C or D.
Probably the most important ………(36)………governing the severity of forest fires is weather . Hot , dry weather lowers the moisture. Once a fire has started , wind is extremely critical ……(37)……….it influences the oxygen supply and the rate of spread. Foresttype and forest conditions …..(38)..…..also important factors. Some fires are caused by lightning; others are caused by people. Those caused by people may be …(39)…..or intentional (incendiary). The causes of fire in the United Statess how large regional differences. In the Rocky Mountains, more than 70% of the fires are caused by lightning, whereas intentional fires mount to only about 1% . In ……(40)…….., more than 40% of the fires in the South are incendiary , whereas lightning causes only 1%.
Trả lời câu hỏi dưới đây:
________(39)