Do I need the prepositions in these sentences?
The exam sheet should only be used to write answers (on).
The blanks should only be used to write answers (in).
The equipment should only be used to test the operation of the system (with).
I feel either way works but it seems to me it is more common to omit the preposition. The versions with prepositions sound better to me though. Are there situations where the prepositions can't be omitted? What rules govern this?
First that all three example seem contrived. Are they your compositions, or where do they come from?
Further, their use of 'only' falls into the same trap afflicting almost every English speaker, however native or erudite. (If that seems pedantic, so is the Question.)
Almost all speakers almost always put 'only' in the wrong place, usually too early.
This is a trivial example yet 'The exam sheet should be used only to write answers' while necessarily being many things other than 'used only for…'
– Robbie Goodwin Sep 17 '23 at 17:02