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