One of the most common forms is, 'If it looks like a duck, swims like a duck, quacks like a duck, then it probably is a duck.' It's just …
If something has all the characteristics of a thing, then it is probably that thing, regardless of how it is presented or what it is called. …
更多内容请点击：DUCK中文(简体)翻译：剑桥词典 - Cambridge Dictionary