English Language & Usage Stack Exchange is a question and answer site for linguists, etymologists, and serious English language enthusiasts. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

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?

share|improve this question

closed as general reference by JSBձոգչ, Kit Z. Fox, 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.

1  
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

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.

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