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 couldn't push you couldn't push he couldn't push we couldn't push you couldn't push they couldn't push
V-ing form
I couldn't be pushing you couldn't be pushing he couldn't be pushing we couldn't be pushing you couldn't be pushing they couldn't be pushing
Perfect
I couldn't have pushed you couldn't have pushed he couldn't have pushed we couldn't have pushed you couldn't have pushed they couldn't have pushed
V-ing perfect
I couldn't have been pushing you couldn't have been pushing he couldn't have been pushing we couldn't have been pushing you couldn't have been pushing they couldn't 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
couldn't I push? couldn't you push? couldn't he push? couldn't we push? couldn't you push? couldn't they push?
V-ing form
couldn't I be pushing? couldn't you be pushing? couldn't he be pushing? couldn't we be pushing? couldn't you be pushing? couldn't they be pushing?
Perfect
couldn't I have pushed? couldn't you have pushed? couldn't he have pushed? couldn't we have pushed? couldn't you have pushed? couldn't they have pushed?
V-ing perfect
couldn't I have been pushing? couldn't you have been pushing? couldn't he have been pushing? couldn't we have been pushing? couldn't you have been pushing? couldn't they have been pushing?