In an Oxford dictionary, ‘must have –ed participle’ is used for supposing a past event.

He must have known (= surely he knew) what she wanted.
I'm sorry, she's not here. She must have left already (= that must be the explanation)
(Advanced Learner’s)

However, a case below seems to have some different meaning. Although, yet, I do not have found the explanation, from a grammar textbook for Korean language, I guess the case seems to express an awareness of realization, perfection, or the continuity of the perfection at present with a past form. Can my guessing be right, or am I to learn about some other explanation?

“Jane,” he recommenced, as we entered the laurel walk, and slowly strayed down in the direction of the sunk fence and the horse-chestnut, “Thornfield is a pleasant place in summer, is it not?”
“Yes, sir.”
“You must have become in some degree attached to the house,—you, who have an eye for natural beauties, and a good deal of the organ of Adhesiveness?”
(Jane Eyre)

  • It's still in the past.
    – Kris
    Apr 1, 2013 at 5:05
  • It's the same: You must have become attached (= surely you became attached)
    – Jim
    Apr 1, 2013 at 5:23

1 Answer 1


Your guess is correct. The present perfect can be used:

1.) to refer to a completed action in the past.

  • She's left.

2.) to refer to a state that began sometime in the past and continues into the present.

  • She's become attached.

The same applies when the present perfect is used with "must" to indicate a deduction:

  • She must have left = I deduce that she has left. [The leaving is completed.]

  • She must have become attached. = I deduce that she has become attached [and still is].

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.