在这个原理被发现之前，工程师们已经制造了利用这个原理的仪器，例如测量船下的海洋深度。

Before this was discovered, engineers had already built instruments to exploit the principle, for example to measure the depth of the sea under a ship.

youdao

在这个原理被发现之前，工程师们已经制造了利用这个原理的仪器，例如测量船下的海洋深度。

Before this was discovered, engineers had already built instruments to exploit the principle, for example to measure the depth of the sea under a ship.

youdao