I know that be + infinitive
is used for ordering, giving instruction, and planning, but some of the example sentences are confusing to me. They are:
Nobody is to open the door. (order)
You are to do your homework before you go out. (order)
I'm to go now. (What's the meaning of this sentence?)
- Mr. Johns was to speak at the meeting last Monday. (Is this sentence about a past plan or obligation?)
You are to be on time. (Is this an order?)
Am I to believe what they say? (Is this sentence an obligation?)
I'm confused because it's said that be + infinitive
is used in giving an order, but I think the meaning is the same to that of 'must'? So, how is 'be + infinitive' different from the meaning of 'must' when giving an order or when there is an obligation? Could you please provide an understandable answer? Thank you in advance.