I could pump you could pump he could pump we could pump you could pump they could pump
V-ing form
I could be pumping you could be pumping he could be pumping we could be pumping you could be pumping they could be pumping
Perfect
I could have pumped you could have pumped he could have pumped we could have pumped you could have pumped they could have pumped
V-ing perfect
I could have been pumping you could have been pumping he could have been pumping we could have been pumping you could have been pumping they could have been pumping
Negation
Simple form
I could not pump you could not pump he could not pump we could not pump you could not pump they could not pump
V-ing form
I could not be pumping you could not be pumping he could not be pumping we could not be pumping you could not be pumping they could not be pumping
Perfect
I could not have pumped you could not have pumped he could not have pumped we could not have pumped you could not have pumped they could not have pumped
V-ing perfect
I could not have been pumping you could not have been pumping he could not have been pumping we could not have been pumping you could not have been pumping they could not have been pumping
Interrogative form
Simple form
could I pump? could you pump? could he pump? could we pump? could you pump? could they pump?
V-ing form
could I be pumping? could you be pumping? could he be pumping? could we be pumping? could you be pumping? could they be pumping?
Perfect
could I have pumped? could you have pumped? could he have pumped? could we have pumped? could you have pumped? could they have pumped?
V-ing perfect
could I have been pumping? could you have been pumping? could he have been pumping? could we have been pumping? could you have been pumping? could they have been pumping?
Interro-negative form
Simple form
could I not pump? could you not pump? could he not pump? could we not pump? could you not pump? could they not pump?
V-ing form
could I not be pumping? could you not be pumping? could he not be pumping? could we not be pumping? could you not be pumping? could they not be pumping?
Perfect
could I not have pumped? could you not have pumped? could he not have pumped? could we not have pumped? could you not have pumped? could they not have pumped?
V-ing perfect
could I not have been pumping? could you not have been pumping? could he not have been pumping? could we not have been pumping? could you not have been pumping? could they not have been pumping?