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