could countersink
Irregular verb: countersink - countersank- countersunk

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could countersink
you could countersink
he could countersink
we could countersink
you could countersink
they could countersink 	I could be countersinking
you could be countersinking
he could be countersinking
we could be countersinking
you could be countersinking
they could be countersinking	I could have countersunk
you could have countersunk
he could have countersunk
we could have countersunk
you could have countersunk
they could have countersunk	I could have been countersinking
you could have been countersinking
he could have been countersinking
we could have been countersinking
you could have been countersinking
they could have been countersinking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't countersink
you couldn't countersink
he couldn't countersink
we couldn't countersink
you couldn't countersink
they couldn't countersink 	I couldn't be countersinking
you couldn't be countersinking
he couldn't be countersinking
we couldn't be countersinking
you couldn't be countersinking
they couldn't be countersinking	I couldn't have countersunk
you couldn't have countersunk
he couldn't have countersunk
we couldn't have countersunk
you couldn't have countersunk
they couldn't have countersunk	I couldn't have been countersinking
you couldn't have been countersinking
he couldn't have been countersinking
we couldn't have been countersinking
you couldn't have been countersinking
they couldn't have been countersinking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I countersink?
could you countersink?
could he countersink?
could we countersink?
could you countersink?
could they countersink? 	could I be countersinking?
could you be countersinking?
could he be countersinking?
could we be countersinking?
could you be countersinking?
could they be countersinking? 	could I have countersunk?
could you have countersunk?
could he have countersunk?
could we have countersunk?
could you have countersunk?
could they have countersunk? 	could I have been countersinking?
could you have been countersinking?
could he have been countersinking?
could we have been countersinking?
could you have been countersinking?
could they have been countersinking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I countersink?
couldn't you countersink?
couldn't he countersink?
couldn't we countersink?
couldn't you countersink?
couldn't they countersink? 	couldn't I be countersinking?
couldn't you be countersinking?
couldn't he be countersinking?
couldn't we be countersinking?
couldn't you be countersinking?
couldn't they be countersinking? 	couldn't I have countersunk?
couldn't you have countersunk?
couldn't he have countersunk?
couldn't we have countersunk?
couldn't you have countersunk?
couldn't they have countersunk? 	couldn't I have been countersinking?
couldn't you have been countersinking?
couldn't he have been countersinking?
couldn't we have been countersinking?
couldn't you have been countersinking?
couldn't they have been countersinking?