To test the theory, the scientists recreated what ancient tool makers might have done by heating a pile of silcrete stone in a fire pit.
为了检验这个理论,科学家们通过在一个火坑里加热砾岩石,重现了远古工匠们可能的做法。
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The first F-35B short takeoff/vertical landing stealth fighter operates in vertical-landing mode on a special "hover pit" at Lockheed Martin in Fort Worth, Texas, during an April test.