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