But no such noise accompanied the quackers.

但是没有这样的噪音伴随着嘎嘎声。

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

第三， 认为嘎嘎声是由来自另一个国家的秘密潜艇造成的想法是站不住脚的。