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 cannot impugn
you cannot impugn
he cannot impugn
we cannot impugn
you cannot impugn
they cannot impugn 	I cannot be impugning
you cannot be impugning
he cannot be impugning
we cannot be impugning
you cannot be impugning
they cannot be impugning	I cannot have impugned
you cannot have impugned
he cannot have impugned
we cannot have impugned
you cannot have impugned
they cannot have impugned	I cannot have been impugning
you cannot have been impugning
he cannot have been impugning
we cannot have been impugning
you cannot have been impugning
they cannot 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 I not impugn?
can you not impugn?
can he not impugn?
can we not impugn?
can you not impugn?
can they not impugn? 	can I not be impugning?
can you not be impugning?
can he not be impugning?
can we not be impugning?
can you not be impugning?
can they not be impugning? 	can I not have impugned?
can you not have impugned?
can he not have impugned?
can we not have impugned?
can you not have impugned?
can they not have impugned? 	can I not have been impugning?
can you not have been impugning?
can he not have been impugning?
can we not have been impugning?
can you not have been impugning?
can they not have been impugning?