I created the following sign for my computer:

"Please do not turn off this computer."

My office mate told me that this should be the correct way to do it:

"Do not turn this computer off."

He said that the preposition should be at the end.
Is he correct?

  • Colloquially, there is no semantic difference between these two phrases. But it is generally accepted that it is bad stylistically to end a sentence with a preposition. Oct 3, 2016 at 16:40
  • The first uses a phrasal verb (turn off), and the second uses an object complement ([to be] off). Both versions work fine. Phrasal verbs can be ambiguous: 'turn (off) the computer' vs 'turn (off the computer)'.
    – AmI
    Oct 3, 2016 at 16:59
  • cf. Preposition Stranding, Examples, against Oct 3, 2016 at 17:00
  • @BladorthinTheGrey No, it's not. Go here: english.stackexchange.com/a/207458/125330
    – deadrat
    Oct 3, 2016 at 17:17

3 Answers 3


The acceptability of "turn NP off" is controlled by the "heaviness" of the NP, as John Ross says in his dissertation. The lightest possible NP is a pronoun, and longer and more complicated NPs are heavier. The light NP "it" in "turn it off" cannot be moved after the particle "off": *"turn off it". The heavy NP in *"turn all the largest computers that all still in the main room off" must be moved to the end.

"This computer" in your example is of medium heaviness, so it needn't be moved to the end, but is heavy enough that it may be moved. Either order of object and particle is acceptable for the phrase you ask about.


Either one is grammatically correct.


Perhaps your office mate meant it's the "preferred" or "more common" way; neither is incorrect in American or British English.

I can think of two points that may help you decide which you'd prefer to use:

First, the phrase "this computer" can be removed entirely (since the meaning of the sign would be obvious in context). Doing so would make the phrases identical, with "turn" and "off" consecutive words.

Second, reversing the composition becomes "Please leave this computer on." The other phrasing, "Please leave on this computer," is awkward.

As an editor, I would go with "Please leave on" or "Please do not turn off" depending on your penchant for brevity. This question really comes down to personal preferences.


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