The lower level – as in the aircraft – is at the disposal of the Economy Class passengers.

在下层机舱内，一切项目都为经济舱的旅客服务。

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One answer appeared in 1969, when the German researcher and writer Erich von Daniken proposed that the lines were drawn by extraterrestrials as runways for their aircraft.

1969年，德国研究人员兼作家埃里希·冯·丹尼肯提出，这些线条是外星人为它们的飞机绘制的跑道。

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They found that the aircraft consumed as much as 15% less fuel (coupled with a reduction in carbon dioxide output).

他们发现，飞机消耗的燃料减少了15%（同时二氧化碳排放量也减少了）。

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Unfortunately, because of the nature of air circulation, any downward-pointing force created aerodynamically generates a backward-pointing resistance in the process just as an increase in the lift of an aircraft wing as the flaps are lowered for take-off or landing creates more drag in the process, forcing the pilot to open the engine throttles to overcome the extra wind resistance.

ECONOMIST: CAR DESIGN

Orders for durable goods in the US fell 5.2% in January, the first fall in five months, as orders for aircraft plunged.

BBC: US durable goods orders fall in January

The PFLP became prominent for a series of major attacks on Israelis in Israel and Europe as well as high-profile aircraft hijackings in the 1960s and 1970s.

CNN: Mustafa Zibri