could gum
Regular verb: gum - gummed- gummed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could gum
you could gum
he could gum
we could gum
you could gum
they could gum 	I could be gumming
you could be gumming
he could be gumming
we could be gumming
you could be gumming
they could be gumming	I could have gummed
you could have gummed
he could have gummed
we could have gummed
you could have gummed
they could have gummed	I could have been gumming
you could have been gumming
he could have been gumming
we could have been gumming
you could have been gumming
they could have been gumming	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not gum
you could not gum
he could not gum
we could not gum
you could not gum
they could not gum 	I could not be gumming
you could not be gumming
he could not be gumming
we could not be gumming
you could not be gumming
they could not be gumming	I could not have gummed
you could not have gummed
he could not have gummed
we could not have gummed
you could not have gummed
they could not have gummed	I could not have been gumming
you could not have been gumming
he could not have been gumming
we could not have been gumming
you could not have been gumming
they could not have been gumming	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I gum?
could you gum?
could he gum?
could we gum?
could you gum?
could they gum? 	could I be gumming?
could you be gumming?
could he be gumming?
could we be gumming?
could you be gumming?
could they be gumming? 	could I have gummed?
could you have gummed?
could he have gummed?
could we have gummed?
could you have gummed?
could they have gummed? 	could I have been gumming?
could you have been gumming?
could he have been gumming?
could we have been gumming?
could you have been gumming?
could they have been gumming? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not gum?
could you not gum?
could he not gum?
could we not gum?
could you not gum?
could they not gum? 	could I not be gumming?
could you not be gumming?
could he not be gumming?
could we not be gumming?
could you not be gumming?
could they not be gumming? 	could I not have gummed?
could you not have gummed?
could he not have gummed?
could we not have gummed?
could you not have gummed?
could they not have gummed? 	could I not have been gumming?
could you not have been gumming?
could he not have been gumming?
could we not have been gumming?
could you not have been gumming?
could they not have been gumming?