I could deepen you could deepen she could deepen we could deepen you could deepen they could deepen
V-ing form
I could be deepening you could be deepening she could be deepening we could be deepening you could be deepening they could be deepening
Perfect
I could have deepened you could have deepened she could have deepened we could have deepened you could have deepened they could have deepened
V-ing perfect
I could have been deepening you could have been deepening she could have been deepening we could have been deepening you could have been deepening they could have been deepening
Negation
Simple form
I could not deepen you could not deepen she could not deepen we could not deepen you could not deepen they could not deepen
V-ing form
I could not be deepening you could not be deepening she could not be deepening we could not be deepening you could not be deepening they could not be deepening
Perfect
I could not have deepened you could not have deepened she could not have deepened we could not have deepened you could not have deepened they could not have deepened
V-ing perfect
I could not have been deepening you could not have been deepening she could not have been deepening we could not have been deepening you could not have been deepening they could not have been deepening
Interrogative form
Simple form
could I deepen? could you deepen? could she deepen? could we deepen? could you deepen? could they deepen?
V-ing form
could I be deepening? could you be deepening? could she be deepening? could we be deepening? could you be deepening? could they be deepening?
Perfect
could I have deepened? could you have deepened? could she have deepened? could we have deepened? could you have deepened? could they have deepened?
V-ing perfect
could I have been deepening? could you have been deepening? could she have been deepening? could we have been deepening? could you have been deepening? could they have been deepening?
Interro-negative form
Simple form
could I not deepen? could you not deepen? could she not deepen? could we not deepen? could you not deepen? could they not deepen?
V-ing form
could I not be deepening? could you not be deepening? could she not be deepening? could we not be deepening? could you not be deepening? could they not be deepening?
Perfect
could I not have deepened? could you not have deepened? could she not have deepened? could we not have deepened? could you not have deepened? could they not have deepened?
V-ing perfect
could I not have been deepening? could you not have been deepening? could she not have been deepening? could we not have been deepening? could you not have been deepening? could they not have been deepening?