English verb conjugation
MUST DOUBT

Regular verb: doubt - doubted - doubted

Affirmation

Simple form	V-ing form
I must doubt you must doubt he must doubt we must doubt you must doubt they must doubt	I must be doubting you must be doubting he must be doubting we must be doubting you must be doubting they must be doubting
Perfect	V-ing perfect
I must have doubted you must have doubted he must have doubted we must have doubted you must have doubted they must have doubted	I must have been doubting you must have been doubting he must have been doubting we must have been doubting you must have been doubting they must have been doubting

Negation

Simple form	V-ing form
I mustn't doubt you mustn't doubt he mustn't doubt we mustn't doubt you mustn't doubt they mustn't doubt	I mustn't be doubting you mustn't be doubting he mustn't be doubting we mustn't be doubting you mustn't be doubting they mustn't be doubting
Perfect	V-ing perfect
I mustn't have doubted you mustn't have doubted he mustn't have doubted we mustn't have doubted you mustn't have doubted they mustn't have doubted	I mustn't have been doubting you mustn't have been doubting he mustn't have been doubting we mustn't have been doubting you mustn't have been doubting they mustn't have been doubting

Interrogative form

Simple form	V-ing form
must I doubt? must you doubt? must he doubt? must we doubt? must you doubt? must they doubt?	must I be doubting? must you be doubting? must he be doubting? must we be doubting? must you be doubting? must they be doubting?
Perfect	V-ing perfect
must I have doubted? must you have doubted? must he have doubted? must we have doubted? must you have doubted? must they have doubted?	must I have been doubting? must you have been doubting? must he have been doubting? must we have been doubting? must you have been doubting? must they have been doubting?

Interro-negative form

Simple form	V-ing form
mustn't I doubt? mustn't you doubt? mustn't he doubt? mustn't we doubt? mustn't you doubt? mustn't they doubt?	mustn't I be doubting? mustn't you be doubting? mustn't he be doubting? mustn't we be doubting? mustn't you be doubting? mustn't they be doubting?
Perfect	V-ing perfect
mustn't I have doubted? mustn't you have doubted? mustn't he have doubted? mustn't we have doubted? mustn't you have doubted? mustn't they have doubted?	mustn't I have been doubting? mustn't you have been doubting? mustn't he have been doubting? mustn't we have been doubting? mustn't you have been doubting? mustn't they have been doubting?