08/09/16 The Use of ‘Supposed To’

use of supposed to

Be supposed + infinitive can be used to talk about what is generally believed.
Examples:
He’s supposed to be quite smart, you know.
This stuff is supposed to kill flies. Let’s try it.

Often, be supposed to is used rather like should, to talk about what people have to do according to the rules or the law, or about what is expected to happen.
Examples:
You’re supposed to start work at 8:30 every morning.
Catholics are supposed to go to church on Sundays.

Be supposed to can express a contrast between what should happen and what actually happens.
Examples:
Lucy was supposed to come to lunch. What’s happened?
Cats are supposed to be afraid of dogs, but our Tibby has just chased Mr Glidewell’s bulldog right down the road.
That’s a lovely picture, but what is it supposed to be?

Not supposed to can refer to prohibitions.
Examples:
You’re not supposed to park on double yellow lines.
People under eighteen aren’t supposed to buy alcoholic drinks.