Eg. First one is:

The room should have cleaned.

And the second one is:

The room should have been cleaned.

What is the difference in terms of their meaning?

  • 1
    Your first version (The room should have cleaned) is not grammatically valid. For a valid Present Tense utterance, there's The room should be cleaned - where the speaker might mean It is desirable / right and proper that someone should clean this room (in the future; it hasn't been done yet) OR It is likely that the room has already been cleaned (as will be discovered shortly, when we look and check the state of the room). OR even It is likely that the room will be cleaned (it isn't yet, but it will be by the time we look at some future time). Tricky stuff, huh? Commented Dec 19, 2018 at 17:10
  • 3
    @FumbleFingers, the first one is indeed grammatically correct, it just doesn't make any sense. "The [subject] should have [verbed]" is perfectly correct, but in this case the verb is not something that the subject would logically do. Rooms don't clean, they are cleaned.
    – T Nguyen
    Commented Dec 19, 2018 at 18:10
  • 1
    @TNguyen: Fair point. Come to that, it's technically possible to contrive a (perhaps futuristic) context where "the room" really could be a credible subject that performs the cleaning - of "itself", or even feasibly of some person or thing specifically put in the "cleaning room" for that very purpose. But I'm not sure it would necessarily be helpful for learners if we restricted "not grammatically valid" to only those constructions that can't conceivably be parsed. Commented Dec 19, 2018 at 19:06
  • I'm curious, @Fumble. Why shouldn't a learner be shown the difference between grammatically sound but apparently nonsensical and makes perfect sense but is grammatically flawed? It seems to me very helpful to restrict the phrase "not grammatically valid" to things that, well, aren't valid for reasons of grammatical form or structure. Commented Dec 20, 2018 at 1:03
  • @GaryBotnovcan: I don't have any bulletproof argument for my position - as you and T Nguyen obviously know, The room should have cleaned is just as "grammatical" as the famous example Colorless green ideas sleep furiously (and considerably easier to contrive a meaningful interpretation! :) I freely admit it was sloppy of me to include the specific word grammatically in my first comment, but as to Why shouldn't learners want to know about it? I can only repeat that I'm not sure it would be helpful to them. Commented Dec 20, 2018 at 14:07

2 Answers 2


Let's simplify this and remove the should have from both examples.

The room cleaned ...

The room was cleaned ...

The second example is a passive voice construction - form of to be + past participle form of verb. This is fine.

The first example is wrong because rooms don't normally clean anything. People clean rooms.

If we don't know who cleaned the room, but know it didn't clean itself magically, that's a perfect case for passive voice and one of the reasons it's used.

Passive voice works with modals like non-passively expressed verbs.

The room is cleaned.

The room must be cleaned.

The room has been cleaned.

The room would have been cleaned.


Another use of the passive voice: When people or an entity does not want to take responsibility for something

Politicians and bosses will use the passive voice:

"Mistakes were made" vs "I made a mistake." or "We made a mistake."

Here, the passive voice was a way to avoid saying...

"The housekeeper should have cleaned the room" (use "should have" in the active)

The room should have BEEN cleaned. (add BEEN to the passive)


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