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