why is "know" expressed as 知っています, and what does 知ります really mean?


> **Possible Duplicate:**  
>  [Why is 知りません the negative form of
> 知っています？](https://japanese.stackexchange.com/questions/5729/why-
> is-%e7%9f%a5%e3%82%8a%e3%81%be%e3%81%9b%e3%82%93-the-negative-form-
> of%e3%80%80%e7%9f%a5%e3%81%a3%e3%81%a6%e3%81%84%e3%81%be%e3%81%99%ef%bc%9f)

I'm posting the question as suggested by Zhen Lin and troyen. What that said,
why is that? And a secondary question, when would you use 知ります?

[Related post](https://japanese.stackexchange.com/q/5729/769)

