could erupt
Regular verb: erupt - erupted- erupted

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could erupt
you could erupt
he could erupt
we could erupt
you could erupt
they could erupt 	I could be erupting
you could be erupting
he could be erupting
we could be erupting
you could be erupting
they could be erupting	I could have erupted
you could have erupted
he could have erupted
we could have erupted
you could have erupted
they could have erupted	I could have been erupting
you could have been erupting
he could have been erupting
we could have been erupting
you could have been erupting
they could have been erupting	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't erupt
you couldn't erupt
he couldn't erupt
we couldn't erupt
you couldn't erupt
they couldn't erupt 	I couldn't be erupting
you couldn't be erupting
he couldn't be erupting
we couldn't be erupting
you couldn't be erupting
they couldn't be erupting	I couldn't have erupted
you couldn't have erupted
he couldn't have erupted
we couldn't have erupted
you couldn't have erupted
they couldn't have erupted	I couldn't have been erupting
you couldn't have been erupting
he couldn't have been erupting
we couldn't have been erupting
you couldn't have been erupting
they couldn't have been erupting	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I erupt?
could you erupt?
could he erupt?
could we erupt?
could you erupt?
could they erupt? 	could I be erupting?
could you be erupting?
could he be erupting?
could we be erupting?
could you be erupting?
could they be erupting? 	could I have erupted?
could you have erupted?
could he have erupted?
could we have erupted?
could you have erupted?
could they have erupted? 	could I have been erupting?
could you have been erupting?
could he have been erupting?
could we have been erupting?
could you have been erupting?
could they have been erupting? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I erupt?
couldn't you erupt?
couldn't he erupt?
couldn't we erupt?
couldn't you erupt?
couldn't they erupt? 	couldn't I be erupting?
couldn't you be erupting?
couldn't he be erupting?
couldn't we be erupting?
couldn't you be erupting?
couldn't they be erupting? 	couldn't I have erupted?
couldn't you have erupted?
couldn't he have erupted?
couldn't we have erupted?
couldn't you have erupted?
couldn't they have erupted? 	couldn't I have been erupting?
couldn't you have been erupting?
couldn't he have been erupting?
couldn't we have been erupting?
couldn't you have been erupting?
couldn't they have been erupting?