After that, we ask a question: “which shortcoming has the second way?” Some students say gasoline barrels may roll aside the road in the middle of the way to the gas station. Some students say gasoline barrels may injure passersby or be bumped to leak gasoline, which pollutes environment or incurs fire. After students answer this question, we conclude that the second transportation way is not a feasible one. For the first and third transportation ways, let’s calculate the efficiency of transportation.