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