I could dog you could dog he could dog we could dog you could dog they could dog
V-ing form
I could be dogging you could be dogging he could be dogging we could be dogging you could be dogging they could be dogging
Perfect
I could have dogged you could have dogged he could have dogged we could have dogged you could have dogged they could have dogged
V-ing perfect
I could have been dogging you could have been dogging he could have been dogging we could have been dogging you could have been dogging they could have been dogging
Negation
Simple form
I could not dog you could not dog he could not dog we could not dog you could not dog they could not dog
V-ing form
I could not be dogging you could not be dogging he could not be dogging we could not be dogging you could not be dogging they could not be dogging
Perfect
I could not have dogged you could not have dogged he could not have dogged we could not have dogged you could not have dogged they could not have dogged
V-ing perfect
I could not have been dogging you could not have been dogging he could not have been dogging we could not have been dogging you could not have been dogging they could not have been dogging
Interrogative form
Simple form
could I dog? could you dog? could he dog? could we dog? could you dog? could they dog?
V-ing form
could I be dogging? could you be dogging? could he be dogging? could we be dogging? could you be dogging? could they be dogging?
Perfect
could I have dogged? could you have dogged? could he have dogged? could we have dogged? could you have dogged? could they have dogged?
V-ing perfect
could I have been dogging? could you have been dogging? could he have been dogging? could we have been dogging? could you have been dogging? could they have been dogging?
Interro-negative form
Simple form
could I not dog? could you not dog? could he not dog? could we not dog? could you not dog? could they not dog?
V-ing form
could I not be dogging? could you not be dogging? could he not be dogging? could we not be dogging? could you not be dogging? could they not be dogging?
Perfect
could I not have dogged? could you not have dogged? could he not have dogged? could we not have dogged? could you not have dogged? could they not have dogged?
V-ing perfect
could I not have been dogging? could you not have been dogging? could he not have been dogging? could we not have been dogging? could you not have been dogging? could they not have been dogging?