We always use a positive tag question after a negative sentence:
You shouldn't take this medicine, should you?
We use a negative tag question after a positive sentence:
She must leave early, mustn't she?
But when there is a negating prefix on the adjective (impatient vs. patient) after the verb "to be", then the sentence is negative in meaning. Does this mean the tag should be positive?
Which is correct, A or B?
A: I am impatient, am I?
B: I am impatient, aren't I?
A: The class was dismissed, was it?
B: The class was dismissed, wasn't it?
Best Answer
The negative prefix on the adjective does not matter, the tag question is determined solely by whether the verb is negative or positive. The correct usage would be "I am impatient, aren't I?" There are occasions for when you could use a positive-positive tag, but it's not really a question (the "up" inflection isn't there). It's used to confirm another person's statement often expressing mocking, doubt, wonder, anger, etc.
Example
Person A: I was sick yesterday and spent the entire day in bed.
Person B: You were sick, were you? Then how come I saw you jogging in the park?
Person A: My wife is going to have a baby.
Person B: She is, is she? Congratulations!