Ａ fire in an enclosed space burns with the aid of reflected radiation that preheats the fuel,making ignition much easier and flames spreading more quickly. yepp4y 说: 其中flames spreading划线 yepp4y 说: 为什么选causing flames to spread而不选causing spreading of the flames？
first, it's parallelism" making ignition much easier and causing flames to spead"second, if you use cause+noun, it should be "causing the spreading of flames"
