I could pile you could pile he could pile we could pile you could pile they could pile
V-ing form
I could be piling you could be piling he could be piling we could be piling you could be piling they could be piling
Perfect
I could have piled you could have piled he could have piled we could have piled you could have piled they could have piled
V-ing perfect
I could have been piling you could have been piling he could have been piling we could have been piling you could have been piling they could have been piling
Negation
Simple form
I could not pile you could not pile he could not pile we could not pile you could not pile they could not pile
V-ing form
I could not be piling you could not be piling he could not be piling we could not be piling you could not be piling they could not be piling
Perfect
I could not have piled you could not have piled he could not have piled we could not have piled you could not have piled they could not have piled
V-ing perfect
I could not have been piling you could not have been piling he could not have been piling we could not have been piling you could not have been piling they could not have been piling
Interrogative form
Simple form
could I pile? could you pile? could he pile? could we pile? could you pile? could they pile?
V-ing form
could I be piling? could you be piling? could he be piling? could we be piling? could you be piling? could they be piling?
Perfect
could I have piled? could you have piled? could he have piled? could we have piled? could you have piled? could they have piled?
V-ing perfect
could I have been piling? could you have been piling? could he have been piling? could we have been piling? could you have been piling? could they have been piling?
Interro-negative form
Simple form
could I not pile? could you not pile? could he not pile? could we not pile? could you not pile? could they not pile?
V-ing form
could I not be piling? could you not be piling? could he not be piling? could we not be piling? could you not be piling? could they not be piling?
Perfect
could I not have piled? could you not have piled? could he not have piled? could we not have piled? could you not have piled? could they not have piled?
V-ing perfect
could I not have been piling? could you not have been piling? could he not have been piling? could we not have been piling? could you not have been piling? could they not have been piling?