I could tinker you could tinker she could tinker we could tinker you could tinker they could tinker
V-ing form
I could be tinkering you could be tinkering she could be tinkering we could be tinkering you could be tinkering they could be tinkering
Perfect
I could have tinkered you could have tinkered she could have tinkered we could have tinkered you could have tinkered they could have tinkered
V-ing perfect
I could have been tinkering you could have been tinkering she could have been tinkering we could have been tinkering you could have been tinkering they could have been tinkering
Negation
Simple form
I could not tinker you could not tinker she could not tinker we could not tinker you could not tinker they could not tinker
V-ing form
I could not be tinkering you could not be tinkering she could not be tinkering we could not be tinkering you could not be tinkering they could not be tinkering
Perfect
I could not have tinkered you could not have tinkered she could not have tinkered we could not have tinkered you could not have tinkered they could not have tinkered
V-ing perfect
I could not have been tinkering you could not have been tinkering she could not have been tinkering we could not have been tinkering you could not have been tinkering they could not have been tinkering
Interrogative form
Simple form
could I tinker? could you tinker? could she tinker? could we tinker? could you tinker? could they tinker?
V-ing form
could I be tinkering? could you be tinkering? could she be tinkering? could we be tinkering? could you be tinkering? could they be tinkering?
Perfect
could I have tinkered? could you have tinkered? could she have tinkered? could we have tinkered? could you have tinkered? could they have tinkered?
V-ing perfect
could I have been tinkering? could you have been tinkering? could she have been tinkering? could we have been tinkering? could you have been tinkering? could they have been tinkering?
Interro-negative form
Simple form
could I not tinker? could you not tinker? could she not tinker? could we not tinker? could you not tinker? could they not tinker?
V-ing form
could I not be tinkering? could you not be tinkering? could she not be tinkering? could we not be tinkering? could you not be tinkering? could they not be tinkering?
Perfect
could I not have tinkered? could you not have tinkered? could she not have tinkered? could we not have tinkered? could you not have tinkered? could they not have tinkered?
V-ing perfect
could I not have been tinkering? could you not have been tinkering? could she not have been tinkering? could we not have been tinkering? could you not have been tinkering? could they not have been tinkering?