I could nod you could nod she could nod we could nod you could nod they could nod
V-ing form
I could be nodding you could be nodding she could be nodding we could be nodding you could be nodding they could be nodding
Perfect
I could have nodded you could have nodded she could have nodded we could have nodded you could have nodded they could have nodded
V-ing perfect
I could have been nodding you could have been nodding she could have been nodding we could have been nodding you could have been nodding they could have been nodding
Negation
Simple form
I could not nod you could not nod she could not nod we could not nod you could not nod they could not nod
V-ing form
I could not be nodding you could not be nodding she could not be nodding we could not be nodding you could not be nodding they could not be nodding
Perfect
I could not have nodded you could not have nodded she could not have nodded we could not have nodded you could not have nodded they could not have nodded
V-ing perfect
I could not have been nodding you could not have been nodding she could not have been nodding we could not have been nodding you could not have been nodding they could not have been nodding
Interrogative form
Simple form
could I nod? could you nod? could she nod? could we nod? could you nod? could they nod?
V-ing form
could I be nodding? could you be nodding? could she be nodding? could we be nodding? could you be nodding? could they be nodding?
Perfect
could I have nodded? could you have nodded? could she have nodded? could we have nodded? could you have nodded? could they have nodded?
V-ing perfect
could I have been nodding? could you have been nodding? could she have been nodding? could we have been nodding? could you have been nodding? could they have been nodding?
Interro-negative form
Simple form
could I not nod? could you not nod? could she not nod? could we not nod? could you not nod? could they not nod?
V-ing form
could I not be nodding? could you not be nodding? could she not be nodding? could we not be nodding? could you not be nodding? could they not be nodding?
Perfect
could I not have nodded? could you not have nodded? could she not have nodded? could we not have nodded? could you not have nodded? could they not have nodded?
V-ing perfect
could I not have been nodding? could you not have been nodding? could she not have been nodding? could we not have been nodding? could you not have been nodding? could they not have been nodding?