I could stock you could stock she could stock we could stock you could stock they could stock
V-ing form
I could be stocking you could be stocking she could be stocking we could be stocking you could be stocking they could be stocking
Perfect
I could have stocked you could have stocked she could have stocked we could have stocked you could have stocked they could have stocked
V-ing perfect
I could have been stocking you could have been stocking she could have been stocking we could have been stocking you could have been stocking they could have been stocking
Negation
Simple form
I couldn't stock you couldn't stock she couldn't stock we couldn't stock you couldn't stock they couldn't stock
V-ing form
I couldn't be stocking you couldn't be stocking she couldn't be stocking we couldn't be stocking you couldn't be stocking they couldn't be stocking
Perfect
I couldn't have stocked you couldn't have stocked she couldn't have stocked we couldn't have stocked you couldn't have stocked they couldn't have stocked
V-ing perfect
I couldn't have been stocking you couldn't have been stocking she couldn't have been stocking we couldn't have been stocking you couldn't have been stocking they couldn't have been stocking
Interrogative form
Simple form
could I stock? could you stock? could she stock? could we stock? could you stock? could they stock?
V-ing form
could I be stocking? could you be stocking? could she be stocking? could we be stocking? could you be stocking? could they be stocking?
Perfect
could I have stocked? could you have stocked? could she have stocked? could we have stocked? could you have stocked? could they have stocked?
V-ing perfect
could I have been stocking? could you have been stocking? could she have been stocking? could we have been stocking? could you have been stocking? could they have been stocking?
Interro-negative form
Simple form
couldn't I stock? couldn't you stock? couldn't she stock? couldn't we stock? couldn't you stock? couldn't they stock?
V-ing form
couldn't I be stocking? couldn't you be stocking? couldn't she be stocking? couldn't we be stocking? couldn't you be stocking? couldn't they be stocking?
Perfect
couldn't I have stocked? couldn't you have stocked? couldn't she have stocked? couldn't we have stocked? couldn't you have stocked? couldn't they have stocked?
V-ing perfect
couldn't I have been stocking? couldn't you have been stocking? couldn't she have been stocking? couldn't we have been stocking? couldn't you have been stocking? couldn't they have been stocking?