could tinker
Regular verb: tinker - tinkered- tinkered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could tinker
you could tinker
he could tinker
we could tinker
you could tinker
they could tinker 	I could be tinkering
you could be tinkering
he could be tinkering
we could be tinkering
you could be tinkering
they could be tinkering	I could have tinkered
you could have tinkered
he could have tinkered
we could have tinkered
you could have tinkered
they could have tinkered	I could have been tinkering
you could have been tinkering
he could have been tinkering
we could have been tinkering
you could have been tinkering
they could have been tinkering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't tinker
you couldn't tinker
he couldn't tinker
we couldn't tinker
you couldn't tinker
they couldn't tinker 	I couldn't be tinkering
you couldn't be tinkering
he couldn't be tinkering
we couldn't be tinkering
you couldn't be tinkering
they couldn't be tinkering	I couldn't have tinkered
you couldn't have tinkered
he couldn't have tinkered
we couldn't have tinkered
you couldn't have tinkered
they couldn't have tinkered	I couldn't have been tinkering
you couldn't have been tinkering
he couldn't have been tinkering
we couldn't have been tinkering
you couldn't have been tinkering
they couldn't have been tinkering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I tinker?
could you tinker?
could he tinker?
could we tinker?
could you tinker?
could they tinker? 	could I be tinkering?
could you be tinkering?
could he be tinkering?
could we be tinkering?
could you be tinkering?
could they be tinkering? 	could I have tinkered?
could you have tinkered?
could he have tinkered?
could we have tinkered?
could you have tinkered?
could they have tinkered? 	could I have been tinkering?
could you have been tinkering?
could he have been tinkering?
could we have been tinkering?
could you have been tinkering?
could they have been tinkering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I tinker?
couldn't you tinker?
couldn't he tinker?
couldn't we tinker?
couldn't you tinker?
couldn't they tinker? 	couldn't I be tinkering?
couldn't you be tinkering?
couldn't he be tinkering?
couldn't we be tinkering?
couldn't you be tinkering?
couldn't they be tinkering? 	couldn't I have tinkered?
couldn't you have tinkered?
couldn't he have tinkered?
couldn't we have tinkered?
couldn't you have tinkered?
couldn't they have tinkered? 	couldn't I have been tinkering?
couldn't you have been tinkering?
couldn't he have been tinkering?
couldn't we have been tinkering?
couldn't you have been tinkering?
couldn't they have been tinkering?