English verb conjugation
COULD DOUBT

Regular verb: doubt - doubted - doubted

Affirmation

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

Negation

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

Interrogative form

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

Interro-negative form

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