What's the difference between 知り合い & 付き合い?


I have answered this 知り合い but in answer's sheet it was 付き合い and I don't get
the difference.

[![enter image description
here](https://i.stack.imgur.com/XdmmJ.jpg)](https://i.stack.imgur.com/XdmmJ.jpg)




Here, 知り合い is not possible because of とは and があります.

彼女は昔の知り合いです would have been fine. However, here, the と after 彼女 indicates that
we have to choose 付き合い, that is because the verb 付き合う takes the particle と.

As for the difference between 付き合い and 知り合い, 知り合い is a mere acquaintance
whereas 付き合い implies a much closer relationship.




知り合い refers to _people_. It means "acquaintance" in the sense of "people who
know each other". It's like "friends" but not so close as 友達.

付き合い refers to _relationship_. It means "acquaintance" in the sense of "the
state of knowing each other". It's close to 交際.

> 彼女とは昔から付き合いがあります。

Literally, "With her, since a long time ago, there has been 付き合い."  
→ I've had 付き合い with her for a long time.

To use 知り合い:

> 彼女とは昔から知り合いです。or  
>  彼女とは昔からの知り合いです。

Literally, "With her, since a long time ago, (I've) been 知り合い."  
→ She and I have been 知り合い for a long time.  
(i.e. She and I have known each other for a long time.)

(彼女とは昔からの付き合いです would be fine, too.)

