1.As a consequence of the present global economic cricis,Boeing's major customer groups(airlines) are lacking in purchasing power.
2.As an US-based Coporation,it is not impossible that customer groups from enemy countries will turn to other suppliers,meanwhile,there is no much advantages when competing with those companies who are sheltered by local protective policies for Boeing.
3.The development in technologyies enable Boeing to produce better aircrafts,for instance,more saving in materials ,reduce the consume of ernegy and provide a safer,more comfortable riding enviroment.
飞行环境是指外部环境,这里明显指的是飞机内的环境舒适性,故换成了”乘坐环境”