The crash of Egypt Air Flight 804, which terrorists may have downed over the Mediterranean Sea, provides another tragic reminder of why.

埃及航空公司的804次航班坠毁的悲剧再一次提醒人们为什么要这么做，那次航班可能是在地中海上空被恐怖分子击落的。

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But it is worth remembering that just over a century ago, heavier-than-air flight seemed an impossible dream.

但是值得回忆的是仅仅在一个世纪以前，重于空气的飞行似乎是个不可能实现的梦想。

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Referring to two helicopters bought by the village for sightseers Zhou li said: 'the air flight project and our new skyscraper are our ways to improve the quality of tourism.

指着两架买来为观光者使用的直升机，周丽说：“这个空中飞行项目和我们新建的摩天楼都是我们来提升旅游质量的举措。”

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Before the flight went down, sensors gave conflicting information on air speed to the plane's computers, possibly because of ice.

VOA: special.2009.06.13

The air pressure in a plane during flight is lower than at sea level.

VOA: special.2009.07.14

The flight was operated for Continental Airlines by another company,Colgan Air.

VOA: special.2009.06.13

But it is worth remembering that just over a century ago, heavier-than-air flight seemed an impossible dream.

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Colgan Air Flight 3407 crashed near Buffalo, New York, on February 12, killing all 49 passengers and crew members aboard.

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