Front a definite object with 把, act on it with the verb, and let 在 + place name where the object comes to rest.
框 · Frame
[subj] 把 [definite obj] [verb] 在 [place]
觸 · Trigger
You move a definite thing and want to say the spot it ends up at.
序 · The move
1Name the actor, then 把 + the definite object.Is the object a specific, known thing?
2Put the placing verb after the object.Does the verb move or set the object somewhere — 放、掛、貼、寫、停?
3Attach 在 + place straight onto the verb.Does 在 PW name where the object comes to rest, after the verb, not before it?
例 · Examples
1我把(fronts the object)書book放place, put在at (where it lands)桌子上on the table。
I put the book down on the table.
界 · Boundary
pre-verb locative 在 (我在桌子上放書)
Pre-verb 在 PW says where the whole event happens; post-verb V在 PW says where the object lands. 我在桌子上寫字 = I write while at the table; 我把字寫在桌子上 = the writing ends up on the table.
plain 把字句 with a result complement (把書放好)
A bare result tail says how the object turned out (放好 = put away properly); 在 PW says the place it turned out at. State reached vs spot reached.
place before the verb: 我把書在桌子上放。 → 我把書放在桌子上。
indefinite object: 我把一本書放在桌子上。 → 我把那本書放在桌子上。
bare verb, no landing spot: 我把書放。 → 我把書放在桌子上。
English packs the placing and the spot into one preposition after the verb ('put the book on the table'); Chinese fronts the object with 把 and hangs 在 + place onto the verb to mark where it settles.