虽然早期的潜艇并不适于航海，但它们直到现在取得了卓越的进步。

Although early submarines were less-than-seaworthy, their progression through present times has been remarkable.

youdao

虽然早期的潜艇并不适于航海，但它们直到现在取得了卓越的进步。

Although early submarines were less-than-seaworthy, their progression through present times has been remarkable.

youdao