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?
Best Answer
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.