Suppose that Bob attends a class at 8 A.M. So if Alice is in the same class at that time she surely sees Bob. But we are not sure whether Alice was at that class yesterday at 8 AM so we don't know whether she saw Bob. I want to tell Alice what would happen according to her presence at that time but I don't know where she was at that time. Conditional sentences type 1 through 3 are used when you are sure about the if clause. What to say when you are not? Are these sentences correct?

If you were in the class at 8 AM you surely saw Bob.

If you have been in the class at 8 AM you have surely seen Bob.

If you had been in the class at 8 AM you had surely seen Bob.

I am in doubt because we don't know the situation is real or unreal in this case.

  • If-conditionals don't presuppose certainty or uncertainty about the if-clause. They simply assert a proposition to be true in the event the if-clause holds.
    – Lawrence
    Jun 4, 2017 at 14:30

1 Answer 1


If you were in the class at 8 AM you must have seen Bob.

is quite possibly in response to a prior statement that the addressee had attended the class, but would be said by someone unsure about their presence.

If you had been in the class at 8 AM you would surely have seen Bob.

is very probably said by someone who believes it likely that the addressee had not attended the class.

  • Thanks. The second sentence that you wrote, seems conditional type 3. What about the first sentence? Is it related to any 3 conditional types?
    – CS.
    Dec 23, 2016 at 10:33
  • Please refer to the treatments of conditional sentences on ELU. Terminology isn't standardised hereabouts. Dec 23, 2016 at 11:26
  • I asked my question there but they migrated my question to here.
    – CS.
    Dec 23, 2016 at 12:06
  • And I'm redirecting you to ELU to check on the usage or not of 'first conditional' etc. (This question would probably have been closed on ELU, either as a duplicate or for lack of research shown. I'm not sure about the requirements here.) Dec 23, 2016 at 12:22
  • @CS. I think Edwin was referring to using the EL&U search facility.
    – Lawrence
    Jun 4, 2017 at 14:23

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