How do you tell whether an item is single-use or can be used repeatedly, and when is it discarded?

Question

Accepted Answer

Items are normally usable any number of times. Only items whose text says to discard them to activate are single-use. An item is discarded only when told to discard it, or when damage or horror equal to its health or sanity is assigned to it.

Arkham Horror

How do you tell whether an item is single-use or can be used repeatedly, and when is it discarded?