If I want to ask my teacher if the lesson should have started earlier, Could I use the sentences below?

1 Wasn´t it supposed to have started 30 minutes ago?

2 Wasn´t it supposed to start 30 minutes ago?

If both are wrong, then what is the difference between 1 and 2?


Both are grammatical. Both are fully idiomatic. Both can describe the same set of circumstances, and be used in the same context.

As usual with questions of aspect in English, the choice is a matter of how the speaker wishes to present the temporal focus.

If the speaker uses the past infinitive here (to have started) they are setting the temporal focus later than the time the lesson should have started. If they use the unmarked form (the simple infinitive to start) they are not setting the temporal focus.

In this case, I can't see any consequences in setting or not setting the focus, and the sentences are interchangeable.

  • 7
    While the two are definitely interchangeable, I think there is often a different shade in meaning. One might use '...to have started...' to imply that this hasn't happened, e.g. "Why isn't the class running? Wasn't it supposed to have started 30 minutes ago?". '...to start...' is more appropriate in the case where you presume it has happened: "Why aren't you at your class? Wasn't it supposed to start 30 minutes ago?" – avid Mar 21 '20 at 2:13
  • @avid that's was helpful to me, I think it would be more useful as an answer – briantist Mar 21 '20 at 3:10
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    The contextual preceding sentences are not the same. @avid says they’re different shade in meaning, but look what happens when they are interchanged. “Why isn’t the class running? Wasn’t it supposed to start 30 minutes ago?”— here “to start” would also imply it hasn’t happened. Let’s look at the other; “Why aren’t you at your class? Wasn’t it supposed to have started 30 minutes ago?”— you can presume it has happened here with “to have started.” But really it’s not the verb tense, It’s the preceding sentence that is changing the meaning. – vol7ron Mar 21 '20 at 11:57
  • @vol7ron I think Avid is trying to say that they feel that it's more appropriate to have the sentences that way around (i.e. "supposed to start" fits better with the "why isnt [...]", and "supposed to have started" fits better with "Why aren't [...]"). I sort of agree, but i'ts a pretty minimal difference. – BeB00 Mar 22 '20 at 9:12
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    I'm sure if I sit here and stare at the two constructions long enough I could convince myself there's a slight difference in meaning, but I'm guessing that if you gave two groups of people a paragraph to read and one group saw construction 1 and the other group construction 2 there wouldn't be a significantly different interpretation of the text between the groups. – eps Mar 22 '20 at 18:28

Colin's answer is right, except that I see — in line with avid's comment — that the different temporal focus indeed indicates a small difference in meaning.

When I say "wasn't it supposed to start 30 minutes ago" I talk about the actual start. A good example would be fireworks where the start would be an event in itself, and everybody is waiting for it.

By contrast, with "wasn't the talk show supposed to have started 30 minutes ago" after switching on the TV I'm focusing on the ongoing talk show after it has started, and less on the start proper.

When speaking casually one could use both tenses interchangeably. I also made an effort to use two examples where the difference really mattered (fireworks have a spectacular start, talk shows do not), which is often not the case.


There is a slight difference in meaning.

You wouldn't use "wasn't it supposed to have started 30 minutes ago" if it started 15 minutes ago and lasted for 5 minutes. "have started" implies that it is still ongoing.

  • I wouldn't use either construction if the event already ended, I see no real difference between the two in that regard. – eps Mar 22 '20 at 18:30

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