関連ワード:
have we drilled to the earth's core have we dug to the earth's core have we ever dug to the earth's core how close have we dug to the earth's core have we drilled through the earth's crust have we drilled past the earth's crust could we drill to the earth's core how deep have we drilled into the earth's core have we dug past the earth's crust have we dug below the earth's crust
