could gum
Regular verb: gum - gummed- gummed

Affirmation 	
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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 	
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I couldn't gum
you couldn't gum
he couldn't gum
we couldn't gum
you couldn't gum
they couldn't gum 	I couldn't be gumming
you couldn't be gumming
he couldn't be gumming
we couldn't be gumming
you couldn't be gumming
they couldn't be gumming	I couldn't have gummed
you couldn't have gummed
he couldn't have gummed
we couldn't have gummed
you couldn't have gummed
they couldn't have gummed	I couldn't have been gumming
you couldn't have been gumming
he couldn't have been gumming
we couldn't have been gumming
you couldn't have been gumming
they couldn't 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 	
couldn't I gum?
couldn't you gum?
couldn't he gum?
couldn't we gum?
couldn't you gum?
couldn't they gum? 	couldn't I be gumming?
couldn't you be gumming?
couldn't he be gumming?
couldn't we be gumming?
couldn't you be gumming?
couldn't they be gumming? 	couldn't I have gummed?
couldn't you have gummed?
couldn't he have gummed?
couldn't we have gummed?
couldn't you have gummed?
couldn't they have gummed? 	couldn't I have been gumming?
couldn't you have been gumming?
couldn't he have been gumming?
couldn't we have been gumming?
couldn't you have been gumming?
couldn't they have been gumming?