flying fortress

• n. 空中堡垒；航行堡垒

flying fortress的用法和样例：

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。