could whiff
Regular verb: whiff - whiffed- whiffed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could whiff
you could whiff
he could whiff
we could whiff
you could whiff
they could whiff 	I could be whiffing
you could be whiffing
he could be whiffing
we could be whiffing
you could be whiffing
they could be whiffing	I could have whiffed
you could have whiffed
he could have whiffed
we could have whiffed
you could have whiffed
they could have whiffed	I could have been whiffing
you could have been whiffing
he could have been whiffing
we could have been whiffing
you could have been whiffing
they could have been whiffing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't whiff
you couldn't whiff
he couldn't whiff
we couldn't whiff
you couldn't whiff
they couldn't whiff 	I couldn't be whiffing
you couldn't be whiffing
he couldn't be whiffing
we couldn't be whiffing
you couldn't be whiffing
they couldn't be whiffing	I couldn't have whiffed
you couldn't have whiffed
he couldn't have whiffed
we couldn't have whiffed
you couldn't have whiffed
they couldn't have whiffed	I couldn't have been whiffing
you couldn't have been whiffing
he couldn't have been whiffing
we couldn't have been whiffing
you couldn't have been whiffing
they couldn't have been whiffing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I whiff?
could you whiff?
could he whiff?
could we whiff?
could you whiff?
could they whiff? 	could I be whiffing?
could you be whiffing?
could he be whiffing?
could we be whiffing?
could you be whiffing?
could they be whiffing? 	could I have whiffed?
could you have whiffed?
could he have whiffed?
could we have whiffed?
could you have whiffed?
could they have whiffed? 	could I have been whiffing?
could you have been whiffing?
could he have been whiffing?
could we have been whiffing?
could you have been whiffing?
could they have been whiffing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I whiff?
couldn't you whiff?
couldn't he whiff?
couldn't we whiff?
couldn't you whiff?
couldn't they whiff? 	couldn't I be whiffing?
couldn't you be whiffing?
couldn't he be whiffing?
couldn't we be whiffing?
couldn't you be whiffing?
couldn't they be whiffing? 	couldn't I have whiffed?
couldn't you have whiffed?
couldn't he have whiffed?
couldn't we have whiffed?
couldn't you have whiffed?
couldn't they have whiffed? 	couldn't I have been whiffing?
couldn't you have been whiffing?
couldn't he have been whiffing?
couldn't we have been whiffing?
couldn't you have been whiffing?
couldn't they have been whiffing?