I could piggyback you could piggyback he could piggyback we could piggyback you could piggyback they could piggyback
V-ing form
I could be piggybacking you could be piggybacking he could be piggybacking we could be piggybacking you could be piggybacking they could be piggybacking
Perfect
I could have piggybacked you could have piggybacked he could have piggybacked we could have piggybacked you could have piggybacked they could have piggybacked
V-ing perfect
I could have been piggybacking you could have been piggybacking he could have been piggybacking we could have been piggybacking you could have been piggybacking they could have been piggybacking
Negation
Simple form
I could not piggyback you could not piggyback he could not piggyback we could not piggyback you could not piggyback they could not piggyback
V-ing form
I could not be piggybacking you could not be piggybacking he could not be piggybacking we could not be piggybacking you could not be piggybacking they could not be piggybacking
Perfect
I could not have piggybacked you could not have piggybacked he could not have piggybacked we could not have piggybacked you could not have piggybacked they could not have piggybacked
V-ing perfect
I could not have been piggybacking you could not have been piggybacking he could not have been piggybacking we could not have been piggybacking you could not have been piggybacking they could not have been piggybacking
Interrogative form
Simple form
could I piggyback? could you piggyback? could he piggyback? could we piggyback? could you piggyback? could they piggyback?
V-ing form
could I be piggybacking? could you be piggybacking? could he be piggybacking? could we be piggybacking? could you be piggybacking? could they be piggybacking?
Perfect
could I have piggybacked? could you have piggybacked? could he have piggybacked? could we have piggybacked? could you have piggybacked? could they have piggybacked?
V-ing perfect
could I have been piggybacking? could you have been piggybacking? could he have been piggybacking? could we have been piggybacking? could you have been piggybacking? could they have been piggybacking?
Interro-negative form
Simple form
could I not piggyback? could you not piggyback? could he not piggyback? could we not piggyback? could you not piggyback? could they not piggyback?
V-ing form
could I not be piggybacking? could you not be piggybacking? could he not be piggybacking? could we not be piggybacking? could you not be piggybacking? could they not be piggybacking?
Perfect
could I not have piggybacked? could you not have piggybacked? could he not have piggybacked? could we not have piggybacked? could you not have piggybacked? could they not have piggybacked?
V-ing perfect
could I not have been piggybacking? could you not have been piggybacking? could he not have been piggybacking? could we not have been piggybacking? could you not have been piggybacking? could they not have been piggybacking?