"When you lie on the floor of an aircraft, you notice a lot of unused space above you," he says. "Even when you're sitting in a plane, there's all this unused empty space above you."

他补充道，当你坐在飞机上时，这些未被利用的空间就在你的头顶。

youdao

Structures of aircraft composite parts include honeycomb, inner contained part, inner empty part, and layered etc.

飞机复合材料零件结构分为蜂窝结构、夹心结构、空心结构、夹层结构等。

youdao

When there are empty seats, it's tempting to move, but there may be passengers still on their way to the aircraft.

有空座位时，有可能换座，但也有可能其它乘客仍在赶往飞机的路上。

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The Manning-led effort began in Atlanta where the airplane was housed early Saturday, with about 20 employee-volunteers from AirTran Airways, flying a mostly empty aircraft to Indianapolis, Indiana, to pick up the supplies.

CNN: Manning brothers team up for Katrina relief

Getting the scheduling wrong imposes a heavy cost: flying half-empty planes or leasing extra aircraft is an expensive business.

ECONOMIST: Algorithms

Without spare pilots or airplanes in New York, the airline decided to fly passengers to Atlanta to swap aircraft and crew rather than fly an empty plane to New York.

WSJ: Flight Nightmares Overshadow Airlines�� Improving Record