飞机搜索后没有发现他们的痕迹，他们被推定已经死亡。
They were presumed dead after search planes found no trace of them.
要找到那架失踪的飞机已经毫无希望，于是中止了搜索。
All hope of finding the missing aircraft was given up and the search abandoned.
尽管广泛的搜索没有被发现的试点或飞机。
Despite a wide ranging search nothing was ever found of the pilot or plane.
研究一种直升飞机的最佳搜索方法。
研究一种直升飞机的最佳搜索方法。
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