flying fortress

• n. 空中堡垒；航行堡垒

例句

用作名词 (n.)

1. The U. S. Army Air Forces believed in daylight bombing with the heavily defended Fortress type of bomber as the backbone of the organization.
   美国陆军航空队，相信在白昼轰炸，应以防御性的空中堡垒重轰炸机为组织之骨干。