第三，蛙叫声来自别国潜水艇的想法也是站不住脚的。

Third, , the idea that the quackers were caused by a secret submarine from another country does not hold up.

youdao

此外，所有的潜水艇都会发现引擎的声音，而且没有并引擎的声音随着蛙叫声。

Also all submarines make some engine noise. But no such noise accompanied the quackers.

youdao

此外，所有的潜水艇都会发现引擎的声音，而且没有并引擎的声音随着蛙叫声。

Also all submarines make some engine noise. But no such noise accompanied the quackers.

youdao