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For example, when the Wright brothers first flew in 1903, all the mechanics and theories necessary — from the piston engine to wing aerodynamics — already existed. The Wrights just had to push the technology a bit further by putting the right parts together and adding some key insights of their own.。业内人士推荐PDF资料作为进阶阅读
Beneath the sea, visibility is low and the radio waves used for radar don’t travel far. The primary tool for detecting submerged objects is sonar.
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