I could plug you could plug she could plug we could plug you could plug they could plug
V-ing form
I could be plugging you could be plugging she could be plugging we could be plugging you could be plugging they could be plugging
Perfect
I could have plugged you could have plugged she could have plugged we could have plugged you could have plugged they could have plugged
V-ing perfect
I could have been plugging you could have been plugging she could have been plugging we could have been plugging you could have been plugging they could have been plugging
Negation
Simple form
I could not plug you could not plug she could not plug we could not plug you could not plug they could not plug
V-ing form
I could not be plugging you could not be plugging she could not be plugging we could not be plugging you could not be plugging they could not be plugging
Perfect
I could not have plugged you could not have plugged she could not have plugged we could not have plugged you could not have plugged they could not have plugged
V-ing perfect
I could not have been plugging you could not have been plugging she could not have been plugging we could not have been plugging you could not have been plugging they could not have been plugging
Interrogative form
Simple form
could I plug? could you plug? could she plug? could we plug? could you plug? could they plug?
V-ing form
could I be plugging? could you be plugging? could she be plugging? could we be plugging? could you be plugging? could they be plugging?
Perfect
could I have plugged? could you have plugged? could she have plugged? could we have plugged? could you have plugged? could they have plugged?
V-ing perfect
could I have been plugging? could you have been plugging? could she have been plugging? could we have been plugging? could you have been plugging? could they have been plugging?
Interro-negative form
Simple form
could I not plug? could you not plug? could she not plug? could we not plug? could you not plug? could they not plug?
V-ing form
could I not be plugging? could you not be plugging? could she not be plugging? could we not be plugging? could you not be plugging? could they not be plugging?
Perfect
could I not have plugged? could you not have plugged? could she not have plugged? could we not have plugged? could you not have plugged? could they not have plugged?
V-ing perfect
could I not have been plugging? could you not have been plugging? could she not have been plugging? could we not have been plugging? could you not have been plugging? could they not have been plugging?