could impugn
Regular verb: impugn - impugned- impugned

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