動詞関連N5
〜てある
has been done (resultative state)
Structure
V-て形（他動詞）+ ある
Explanation
Indicates the continuing state resulting from a completed action. Transitive verb + てある = state persists after someone deliberately did something. Differs from 〜ている in implying "someone did it".
Examples
窓が開けてあります。
The window is open. (Someone opened it.)
机の上に手紙が置いてありました。
A letter was placed on the desk. (Someone put it there.)
Note
てある=transitive+ある (someone did it); ている=intransitive+いる (natural state). かけてある=hung by someone; かかっている=is hanging.