"Must (Probability)" has this structure: "must have PP". But can "Must (Obligation)" have that structure?
Ok, now, must (Probability) can be used to express the high probability
Ex: She must be on the bus. (I'm fairly sure this is a good guess)
& in the past: She must have been on the bus yesterday. (I'm fairly sure this is a good guess)
But, must (obligation) can be used to express strong obligation
Ex: She must study today.
& in the past: She had to study yesterday (as in textbook)
My question is that:
Can "Must (Obligation)" have the structure "must have PP"?
So, is "She had to study yesterday" (as in textbook) the same as "She must have studied yesterday"?
Or, whenever we say "She must have studied yesterday", people will think "must" here refers to a Probability?