However, air transportation is the most expensive mode of transportation, especially for the short-haul routes, say in Europe, where the economic cruising speed cannot be achieved.

• 译文：然而，空运是最昂贵的运输模式，特别对于那些短途路线来说，好比在欧洲说吧，在那，最省燃料的速度航行都没能够实现。