I could decide you could decide he could decide we could decide you could decide they could decide
V-ing form
I could be deciding you could be deciding he could be deciding we could be deciding you could be deciding they could be deciding
Perfect
I could have decided you could have decided he 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 he 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 he 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 he 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 he 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 he 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 he decide? could we decide? could you decide? could they decide?
V-ing form
could I be deciding? could you be deciding? could he be deciding? could we be deciding? could you be deciding? could they be deciding?
Perfect
could I have decided? could you have decided? could he 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 he 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 he 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 he 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 he 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 he have been deciding? couldn't we have been deciding? couldn't you have been deciding? couldn't they have been deciding?