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