could headbutt
Regular verb: headbutt - headbutted- headbutted

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could headbutt
you could headbutt
he could headbutt
we could headbutt
you could headbutt
they could headbutt 	I could be headbutting
you could be headbutting
he could be headbutting
we could be headbutting
you could be headbutting
they could be headbutting	I could have headbutted
you could have headbutted
he could have headbutted
we could have headbutted
you could have headbutted
they could have headbutted	I could have been headbutting
you could have been headbutting
he could have been headbutting
we could have been headbutting
you could have been headbutting
they could have been headbutting	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't headbutt
you couldn't headbutt
he couldn't headbutt
we couldn't headbutt
you couldn't headbutt
they couldn't headbutt 	I couldn't be headbutting
you couldn't be headbutting
he couldn't be headbutting
we couldn't be headbutting
you couldn't be headbutting
they couldn't be headbutting	I couldn't have headbutted
you couldn't have headbutted
he couldn't have headbutted
we couldn't have headbutted
you couldn't have headbutted
they couldn't have headbutted	I couldn't have been headbutting
you couldn't have been headbutting
he couldn't have been headbutting
we couldn't have been headbutting
you couldn't have been headbutting
they couldn't have been headbutting	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I headbutt?
could you headbutt?
could he headbutt?
could we headbutt?
could you headbutt?
could they headbutt? 	could I be headbutting?
could you be headbutting?
could he be headbutting?
could we be headbutting?
could you be headbutting?
could they be headbutting? 	could I have headbutted?
could you have headbutted?
could he have headbutted?
could we have headbutted?
could you have headbutted?
could they have headbutted? 	could I have been headbutting?
could you have been headbutting?
could he have been headbutting?
could we have been headbutting?
could you have been headbutting?
could they have been headbutting? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I headbutt?
couldn't you headbutt?
couldn't he headbutt?
couldn't we headbutt?
couldn't you headbutt?
couldn't they headbutt? 	couldn't I be headbutting?
couldn't you be headbutting?
couldn't he be headbutting?
couldn't we be headbutting?
couldn't you be headbutting?
couldn't they be headbutting? 	couldn't I have headbutted?
couldn't you have headbutted?
couldn't he have headbutted?
couldn't we have headbutted?
couldn't you have headbutted?
couldn't they have headbutted? 	couldn't I have been headbutting?
couldn't you have been headbutting?
couldn't he have been headbutting?
couldn't we have been headbutting?
couldn't you have been headbutting?
couldn't they have been headbutting?