I could push you could push he could push we could push you could push they could push
V-ing form
I could be pushing you could be pushing he could be pushing we could be pushing you could be pushing they could be pushing
Perfect
I could have pushed you could have pushed he could have pushed we could have pushed you could have pushed they could have pushed
V-ing perfect
I could have been pushing you could have been pushing he could have been pushing we could have been pushing you could have been pushing they could have been pushing
Negation
Simple form
I could not push you could not push he could not push we could not push you could not push they could not push
V-ing form
I could not be pushing you could not be pushing he could not be pushing we could not be pushing you could not be pushing they could not be pushing
Perfect
I could not have pushed you could not have pushed he could not have pushed we could not have pushed you could not have pushed they could not have pushed
V-ing perfect
I could not have been pushing you could not have been pushing he could not have been pushing we could not have been pushing you could not have been pushing they could not have been pushing
Interrogative form
Simple form
could I push? could you push? could he push? could we push? could you push? could they push?
V-ing form
could I be pushing? could you be pushing? could he be pushing? could we be pushing? could you be pushing? could they be pushing?
Perfect
could I have pushed? could you have pushed? could he have pushed? could we have pushed? could you have pushed? could they have pushed?
V-ing perfect
could I have been pushing? could you have been pushing? could he have been pushing? could we have been pushing? could you have been pushing? could they have been pushing?
Interro-negative form
Simple form
could I not push? could you not push? could he not push? could we not push? could you not push? could they not push?
V-ing form
could I not be pushing? could you not be pushing? could he not be pushing? could we not be pushing? could you not be pushing? could they not be pushing?
Perfect
could I not have pushed? could you not have pushed? could he not have pushed? could we not have pushed? could you not have pushed? could they not have pushed?
V-ing perfect
could I not have been pushing? could you not have been pushing? could he not have been pushing? could we not have been pushing? could you not have been pushing? could they not have been pushing?