could deepen
Regular verb: deepen - deepened- deepened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could deepen
you could deepen
he could deepen
we could deepen
you could deepen
they could deepen 	I could be deepening
you could be deepening
he could be deepening
we could be deepening
you could be deepening
they could be deepening	I could have deepened
you could have deepened
he could have deepened
we could have deepened
you could have deepened
they could have deepened	I could have been deepening
you could have been deepening
he could have been deepening
we could have been deepening
you could have been deepening
they could have been deepening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't deepen
you couldn't deepen
he couldn't deepen
we couldn't deepen
you couldn't deepen
they couldn't deepen 	I couldn't be deepening
you couldn't be deepening
he couldn't be deepening
we couldn't be deepening
you couldn't be deepening
they couldn't be deepening	I couldn't have deepened
you couldn't have deepened
he couldn't have deepened
we couldn't have deepened
you couldn't have deepened
they couldn't have deepened	I couldn't have been deepening
you couldn't have been deepening
he couldn't have been deepening
we couldn't have been deepening
you couldn't have been deepening
they couldn't have been deepening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I deepen?
could you deepen?
could he deepen?
could we deepen?
could you deepen?
could they deepen? 	could I be deepening?
could you be deepening?
could he be deepening?
could we be deepening?
could you be deepening?
could they be deepening? 	could I have deepened?
could you have deepened?
could he have deepened?
could we have deepened?
could you have deepened?
could they have deepened? 	could I have been deepening?
could you have been deepening?
could he have been deepening?
could we have been deepening?
could you have been deepening?
could they have been deepening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I deepen?
couldn't you deepen?
couldn't he deepen?
couldn't we deepen?
couldn't you deepen?
couldn't they deepen? 	couldn't I be deepening?
couldn't you be deepening?
couldn't he be deepening?
couldn't we be deepening?
couldn't you be deepening?
couldn't they be deepening? 	couldn't I have deepened?
couldn't you have deepened?
couldn't he have deepened?
couldn't we have deepened?
couldn't you have deepened?
couldn't they have deepened? 	couldn't I have been deepening?
couldn't you have been deepening?
couldn't he have been deepening?
couldn't we have been deepening?
couldn't you have been deepening?
couldn't they have been deepening?