I could stretch you could stretch he could stretch we could stretch you could stretch they could stretch
V-ing form
I could be stretching you could be stretching he could be stretching we could be stretching you could be stretching they could be stretching
Perfect
I could have stretched you could have stretched he could have stretched we could have stretched you could have stretched they could have stretched
V-ing perfect
I could have been stretching you could have been stretching he could have been stretching we could have been stretching you could have been stretching they could have been stretching
Negation
Simple form
I could not stretch you could not stretch he could not stretch we could not stretch you could not stretch they could not stretch
V-ing form
I could not be stretching you could not be stretching he could not be stretching we could not be stretching you could not be stretching they could not be stretching
Perfect
I could not have stretched you could not have stretched he could not have stretched we could not have stretched you could not have stretched they could not have stretched
V-ing perfect
I could not have been stretching you could not have been stretching he could not have been stretching we could not have been stretching you could not have been stretching they could not have been stretching
Interrogative form
Simple form
could I stretch? could you stretch? could he stretch? could we stretch? could you stretch? could they stretch?
V-ing form
could I be stretching? could you be stretching? could he be stretching? could we be stretching? could you be stretching? could they be stretching?
Perfect
could I have stretched? could you have stretched? could he have stretched? could we have stretched? could you have stretched? could they have stretched?
V-ing perfect
could I have been stretching? could you have been stretching? could he have been stretching? could we have been stretching? could you have been stretching? could they have been stretching?
Interro-negative form
Simple form
could I not stretch? could you not stretch? could he not stretch? could we not stretch? could you not stretch? could they not stretch?
V-ing form
could I not be stretching? could you not be stretching? could he not be stretching? could we not be stretching? could you not be stretching? could they not be stretching?
Perfect
could I not have stretched? could you not have stretched? could he not have stretched? could we not have stretched? could you not have stretched? could they not have stretched?
V-ing perfect
could I not have been stretching? could you not have been stretching? could he not have been stretching? could we not have been stretching? could you not have been stretching? could they not have been stretching?