English verb conjugation
COULD IMPUGN

Regular verb: impugn - impugned - impugned

Affirmation

Simple form	V-ing form
I could impugn you could impugn he could impugn we could impugn you could impugn they could impugn	I could be impugning you could be impugning he could be impugning we could be impugning you could be impugning they could be impugning
Perfect	V-ing perfect
I could have impugned you could have impugned he could have impugned we could have impugned you could have impugned they could have impugned	I could have been impugning you could have been impugning he could have been impugning we could have been impugning you could have been impugning they could have been impugning

Negation

Simple form	V-ing form
I couldn't impugn you couldn't impugn he couldn't impugn we couldn't impugn you couldn't impugn they couldn't impugn	I couldn't be impugning you couldn't be impugning he couldn't be impugning we couldn't be impugning you couldn't be impugning they couldn't be impugning
Perfect	V-ing perfect
I couldn't have impugned you couldn't have impugned he couldn't have impugned we couldn't have impugned you couldn't have impugned they couldn't have impugned	I couldn't have been impugning you couldn't have been impugning he couldn't have been impugning we couldn't have been impugning you couldn't have been impugning they couldn't have been impugning

Interrogative form

Simple form	V-ing form
could I impugn? could you impugn? could he impugn? could we impugn? could you impugn? could they impugn?	could I be impugning? could you be impugning? could he be impugning? could we be impugning? could you be impugning? could they be impugning?
Perfect	V-ing perfect
could I have impugned? could you have impugned? could he have impugned? could we have impugned? could you have impugned? could they have impugned?	could I have been impugning? could you have been impugning? could he have been impugning? could we have been impugning? could you have been impugning? could they have been impugning?

Interro-negative form

Simple form	V-ing form
couldn't I impugn? couldn't you impugn? couldn't he impugn? couldn't we impugn? couldn't you impugn? couldn't they impugn?	couldn't I be impugning? couldn't you be impugning? couldn't he be impugning? couldn't we be impugning? couldn't you be impugning? couldn't they be impugning?
Perfect	V-ing perfect
couldn't I have impugned? couldn't you have impugned? couldn't he have impugned? couldn't we have impugned? couldn't you have impugned? couldn't they have impugned?	couldn't I have been impugning? couldn't you have been impugning? couldn't he have been impugning? couldn't we have been impugning? couldn't you have been impugning? couldn't they have been impugning?