How are people to know?

[optimistic pessimist]

Dear all,

I'd like to aske about the use of "be to+verb" in the passage below.

[About seeing the border from the air] But if there aren't any trenches or anything, how are people to know? I mean, where's the difference then? And if there's no difference both sides will be the same; it'll be just like it used to be before, when we used to catch a train in Dhaka and get off in Calcutta the next day...


If you are to say "how are people to know" in other words, which is the closest in meaning?

1. how can people know
2. how are people going to know
3. how will people be required to know

Thank you!

OP

[SoothingDave]

2