I could ship you could ship he could ship we could ship you could ship they could ship
V-ing form
I could be shipping you could be shipping he could be shipping we could be shipping you could be shipping they could be shipping
Perfect
I could have shipped you could have shipped he could have shipped we could have shipped you could have shipped they could have shipped
V-ing perfect
I could have been shipping you could have been shipping he could have been shipping we could have been shipping you could have been shipping they could have been shipping
Negation
Simple form
I couldn't ship you couldn't ship he couldn't ship we couldn't ship you couldn't ship they couldn't ship
V-ing form
I couldn't be shipping you couldn't be shipping he couldn't be shipping we couldn't be shipping you couldn't be shipping they couldn't be shipping
Perfect
I couldn't have shipped you couldn't have shipped he couldn't have shipped we couldn't have shipped you couldn't have shipped they couldn't have shipped
V-ing perfect
I couldn't have been shipping you couldn't have been shipping he couldn't have been shipping we couldn't have been shipping you couldn't have been shipping they couldn't have been shipping
Interrogative form
Simple form
could I ship? could you ship? could he ship? could we ship? could you ship? could they ship?
V-ing form
could I be shipping? could you be shipping? could he be shipping? could we be shipping? could you be shipping? could they be shipping?
Perfect
could I have shipped? could you have shipped? could he have shipped? could we have shipped? could you have shipped? could they have shipped?
V-ing perfect
could I have been shipping? could you have been shipping? could he have been shipping? could we have been shipping? could you have been shipping? could they have been shipping?
Interro-negative form
Simple form
couldn't I ship? couldn't you ship? couldn't he ship? couldn't we ship? couldn't you ship? couldn't they ship?
V-ing form
couldn't I be shipping? couldn't you be shipping? couldn't he be shipping? couldn't we be shipping? couldn't you be shipping? couldn't they be shipping?
Perfect
couldn't I have shipped? couldn't you have shipped? couldn't he have shipped? couldn't we have shipped? couldn't you have shipped? couldn't they have shipped?
V-ing perfect
couldn't I have been shipping? couldn't you have been shipping? couldn't he have been shipping? couldn't we have been shipping? couldn't you have been shipping? couldn't they have been shipping?