could tarnish
Regular verb: tarnish - tarnished- tarnished

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could tarnish
you could tarnish
she could tarnish
we could tarnish
you could tarnish
they could tarnish 	I could be tarnishing
you could be tarnishing
she could be tarnishing
we could be tarnishing
you could be tarnishing
they could be tarnishing	I could have tarnished
you could have tarnished
she could have tarnished
we could have tarnished
you could have tarnished
they could have tarnished	I could have been tarnishing
you could have been tarnishing
she could have been tarnishing
we could have been tarnishing
you could have been tarnishing
they could have been tarnishing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not tarnish
you could not tarnish
she could not tarnish
we could not tarnish
you could not tarnish
they could not tarnish 	I could not be tarnishing
you could not be tarnishing
she could not be tarnishing
we could not be tarnishing
you could not be tarnishing
they could not be tarnishing	I could not have tarnished
you could not have tarnished
she could not have tarnished
we could not have tarnished
you could not have tarnished
they could not have tarnished	I could not have been tarnishing
you could not have been tarnishing
she could not have been tarnishing
we could not have been tarnishing
you could not have been tarnishing
they could not have been tarnishing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I tarnish?
could you tarnish?
could she tarnish?
could we tarnish?
could you tarnish?
could they tarnish? 	could I be tarnishing?
could you be tarnishing?
could she be tarnishing?
could we be tarnishing?
could you be tarnishing?
could they be tarnishing? 	could I have tarnished?
could you have tarnished?
could she have tarnished?
could we have tarnished?
could you have tarnished?
could they have tarnished? 	could I have been tarnishing?
could you have been tarnishing?
could she have been tarnishing?
could we have been tarnishing?
could you have been tarnishing?
could they have been tarnishing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not tarnish?
could you not tarnish?
could she not tarnish?
could we not tarnish?
could you not tarnish?
could they not tarnish? 	could I not be tarnishing?
could you not be tarnishing?
could she not be tarnishing?
could we not be tarnishing?
could you not be tarnishing?
could they not be tarnishing? 	could I not have tarnished?
could you not have tarnished?
could she not have tarnished?
could we not have tarnished?
could you not have tarnished?
could they not have tarnished? 	could I not have been tarnishing?
could you not have been tarnishing?
could she not have been tarnishing?
could we not have been tarnishing?
could you not have been tarnishing?
could they not have been tarnishing?