試題詳解

48. According to article, which of the following cases will be considered relatively harmless?
(A)When a mass of solid materials is grounded into a fine powder and intimately mixed with air in the form of dust cloud.
(B) When a mass of materials is released rapidly with ignition.
(C) When a mass of materials is dissipated with gaseous effect.
(D) When a mass of solid materials is heated gradually and slowly.