“second-trip echo”的概念、定义、翻译、参考文献-科学参考

单词	second-trip echo
释义	second-trip echo [`sek·ǝnd ¦trip ´ek·ō] See <<second-time-around echo>>
随便看	drag direction drag factor drag fold drag force dragging of inertial frames drag-in dragline dragline conveyor dragline excavator dragline scraper drag link drag mark Dragon dragonfly drag-out drag parachute drag rope dragsaw drag-stone mill drag technique drag truss drag-type tachometer drag-weight ratio drag wire drain

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