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 must not doubt you must not doubt he must not doubt we must not doubt you must not doubt they must not doubt	I must not be doubting you must not be doubting he must not be doubting we must not be doubting you must not be doubting they must not be doubting
Perfect	V-ing perfect
I must not have doubted you must not have doubted he must not have doubted we must not have doubted you must not have doubted they must not have doubted	I must not have been doubting you must not have been doubting he must not have been doubting we must not have been doubting you must not have been doubting they must not 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
must I not doubt? must you not doubt? must he not doubt? must we not doubt? must you not doubt? must they not doubt?	must I not be doubting? must you not be doubting? must he not be doubting? must we not be doubting? must you not be doubting? must they not be doubting?
Perfect	V-ing perfect
must I not have doubted? must you not have doubted? must he not have doubted? must we not have doubted? must you not have doubted? must they not have doubted?	must I not have been doubting? must you not have been doubting? must he not have been doubting? must we not have been doubting? must you not have been doubting? must they not have been doubting?