I could prepare you could prepare she could prepare we could prepare you could prepare they could prepare
V-ing form
I could be preparing you could be preparing she could be preparing we could be preparing you could be preparing they could be preparing
Perfect
I could have prepared you could have prepared she 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 she 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 she 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 she 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 she 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 she 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 she prepare? could we prepare? could you prepare? could they prepare?
V-ing form
could I be preparing? could you be preparing? could she be preparing? could we be preparing? could you be preparing? could they be preparing?
Perfect
could I have prepared? could you have prepared? could she 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 she 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 she 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 she 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 she 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 she have been preparing? couldn't we have been preparing? couldn't you have been preparing? couldn't they have been preparing?