can impugn
Regular verb: impugn - impugned- impugned

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

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

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

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