I could regenerate you could regenerate he could regenerate we could regenerate you could regenerate they could regenerate
V-ing form
I could be regenerating you could be regenerating he could be regenerating we could be regenerating you could be regenerating they could be regenerating
Perfect
I could have regenerated you could have regenerated he could have regenerated we could have regenerated you could have regenerated they could have regenerated
V-ing perfect
I could have been regenerating you could have been regenerating he could have been regenerating we could have been regenerating you could have been regenerating they could have been regenerating
Negation
Simple form
I couldn't regenerate you couldn't regenerate he couldn't regenerate we couldn't regenerate you couldn't regenerate they couldn't regenerate
V-ing form
I couldn't be regenerating you couldn't be regenerating he couldn't be regenerating we couldn't be regenerating you couldn't be regenerating they couldn't be regenerating
Perfect
I couldn't have regenerated you couldn't have regenerated he couldn't have regenerated we couldn't have regenerated you couldn't have regenerated they couldn't have regenerated
V-ing perfect
I couldn't have been regenerating you couldn't have been regenerating he couldn't have been regenerating we couldn't have been regenerating you couldn't have been regenerating they couldn't have been regenerating
Interrogative form
Simple form
could I regenerate? could you regenerate? could he regenerate? could we regenerate? could you regenerate? could they regenerate?
V-ing form
could I be regenerating? could you be regenerating? could he be regenerating? could we be regenerating? could you be regenerating? could they be regenerating?
Perfect
could I have regenerated? could you have regenerated? could he have regenerated? could we have regenerated? could you have regenerated? could they have regenerated?
V-ing perfect
could I have been regenerating? could you have been regenerating? could he have been regenerating? could we have been regenerating? could you have been regenerating? could they have been regenerating?
Interro-negative form
Simple form
couldn't I regenerate? couldn't you regenerate? couldn't he regenerate? couldn't we regenerate? couldn't you regenerate? couldn't they regenerate?
V-ing form
couldn't I be regenerating? couldn't you be regenerating? couldn't he be regenerating? couldn't we be regenerating? couldn't you be regenerating? couldn't they be regenerating?
Perfect
couldn't I have regenerated? couldn't you have regenerated? couldn't he have regenerated? couldn't we have regenerated? couldn't you have regenerated? couldn't they have regenerated?
V-ing perfect
couldn't I have been regenerating? couldn't you have been regenerating? couldn't he have been regenerating? couldn't we have been regenerating? couldn't you have been regenerating? couldn't they have been regenerating?