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If someone says that they had been to Florida on a recent trip, which one of the following would be a correct respone:

  • That must had been fun.

  • That must have been fun.

Or is there a better way of saying this?

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closed as general reference by JSBձոգչ, KitFox, MετάEd, jwpat7, FumbleFingers Jan 27 '12 at 3:52

This question is too basic; it can be definitively and permanently answered by a single link to a standard internet reference source designed specifically to find that type of information.If this question can be reworded to fit the rules in the help center, please edit the question.

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The correct answer is must have. This is a very basic fact of English grammar, so unless you can give some specific indication of what's confusing you, this will be closed as "general reference". –  JSBձոգչ Jan 27 '12 at 1:50
    
@JSBᾶngs: I know it's simple but there are differences when it comes to imaginary situation, past habitual situation, and future predication. I don't know which one goes where. I am the guy who is lost in tenses. –  user17857 Jan 27 '12 at 3:54

1 Answer 1

After modal auxiliary verbs like must, you use the plain form of the verb. But had is the past tense/participle form, so it can't go here. Only must have is correct.

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What would we use if we were talking about an imaginary and future situations? –  user17857 Jan 27 '12 at 3:52