関連ワード:  why do we need transport class 2    why do we need transport class 2 short answer    why do we need means of transport class 2    why do we need means of transport class 2 answer    why do we need different means of transport class 2    why do we need different means of transport class 2 short answer    why do we need air transport for class 2    why do we need the means of water transport class 2    why do we need different types of transport for class 2    why do we need means of transport class 3