A supposed spy; the supposed decline of culture.
The movie is supposed to be good.
You are not supposed to smoke in the restaurant. [Note: this means, you are obliged not to smoke.]
The phone is supposed to come with a manual.
An example of supposed used as an adjective is in the phrase "his supposed girlfriend," which means a woman who he says is his girlfriend but whom no one else has ever met before.
Medication that is supposed to relieve pain.