How can I distinguish the particle で from the て form of です?


> 雨で出かけられない。

Can't で in this kind of sentences be both?

> 雨 + で (particle) + 出かけられない。  
>  Because it's raining, I can't go out.

> 雨 + で (て form) + 出かけられない。  
>  (雨です。出かけられない。)  
>  It's raining, (and, then) I can't go out.




In this simple sentence, this で is a particle, not the te-form of だ. There is
no reason to parse it as a compound sentence that has two main clauses.

To interpret it as the te-form of だ, you need to indicate it belongs to
another clause in some way or another. For example,

> あいにく今日は雨で、(私は)出かけられない。

Here 雨で clearly belongs to a different clause with a different topic (今日), so
this is a compound sentence with two main clauses. (I also added a comma,
which is not strictly necessary but works as a hint that there is a "break"
after the で.)

When で is the te-form, you should be able to use also でして (te-form of です) and
であって (te-form of である) naturally:

> あいにく今日は雨でして、出かけられません。  
>  あいにく今日は雨であって、出かけられない。

Related:

  * [Is the で in というわけで the de-particle or the te-form of だ?](https://japanese.stackexchange.com/q/83727/5010)




In this simple sentence, this で is a particle, not the te-form of だ. There is
no reason to parse it as a compound sentence that has two main clauses.

To interpret it as the te-form of だ, you need to indicate it belongs to
another clause in some way or another. For example,

> あいにく今日は雨で、(私は)出かけられない。

Here 雨で clearly belongs to a different clause with a different topic (今日), so
this is a compound sentence with two main clauses. (I also added a comma,
which is not strictly necessary but works as a hint that there is a "break"
after the で.)

When で is the te-form, you should be able to use also でして (te-form of です) and
であって (te-form of である) naturally:

> あいにく今日は雨でして、出かけられません。  
>  あいにく今日は雨であって、出かけられない。

Related:

  * [Is the で in というわけで the de-particle or the te-form of だ?](https://japanese.stackexchange.com/q/83727/5010)

