These structures had been detected years earlier by echo-sounding instruments, but they had never been penetrated in the course of drilling.

这些结构在早些年曾被回声探测器探测到，但是它们从未被钻探过。

youdao

I asked, my voice sounding like a shrill echo.

我问。我的声音象是尖利的回声。

youdao

I asked, my voice sounding like a shrill echo.

我问。我的声音象是尖利的回声。

youdao