could thumbtack
Verbe régulier : thumbtack - thumbtacked- thumbtacked

Affirmation 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
I could thumbtack
you could thumbtack
he could thumbtack
we could thumbtack
you could thumbtack
they could thumbtack 	I could be thumbtacking
you could be thumbtacking
he could be thumbtacking
we could be thumbtacking
you could be thumbtacking
they could be thumbtacking	I could have thumbtacked
you could have thumbtacked
he could have thumbtacked
we could have thumbtacked
you could have thumbtacked
they could have thumbtacked	I could have been thumbtacking
you could have been thumbtacking
he could have been thumbtacking
we could have been thumbtacking
you could have been thumbtacking
they could have been thumbtacking	

Négation 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
I couldn't thumbtack
you couldn't thumbtack
he couldn't thumbtack
we couldn't thumbtack
you couldn't thumbtack
they couldn't thumbtack 	I couldn't be thumbtacking
you couldn't be thumbtacking
he couldn't be thumbtacking
we couldn't be thumbtacking
you couldn't be thumbtacking
they couldn't be thumbtacking	I couldn't have thumbtacked
you couldn't have thumbtacked
he couldn't have thumbtacked
we couldn't have thumbtacked
you couldn't have thumbtacked
they couldn't have thumbtacked	I couldn't have been thumbtacking
you couldn't have been thumbtacking
he couldn't have been thumbtacking
we couldn't have been thumbtacking
you couldn't have been thumbtacking
they couldn't have been thumbtacking	

Forme interrogative 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
could I thumbtack?
could you thumbtack?
could he thumbtack?
could we thumbtack?
could you thumbtack?
could they thumbtack? 	could I be thumbtacking?
could you be thumbtacking?
could he be thumbtacking?
could we be thumbtacking?
could you be thumbtacking?
could they be thumbtacking? 	could I have thumbtacked?
could you have thumbtacked?
could he have thumbtacked?
could we have thumbtacked?
could you have thumbtacked?
could they have thumbtacked? 	could I have been thumbtacking?
could you have been thumbtacking?
could he have been thumbtacking?
could we have been thumbtacking?
could you have been thumbtacking?
could they have been thumbtacking? 	

Forme interro-négative 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
couldn't I thumbtack?
couldn't you thumbtack?
couldn't he thumbtack?
couldn't we thumbtack?
couldn't you thumbtack?
couldn't they thumbtack? 	couldn't I be thumbtacking?
couldn't you be thumbtacking?
couldn't he be thumbtacking?
couldn't we be thumbtacking?
couldn't you be thumbtacking?
couldn't they be thumbtacking? 	couldn't I have thumbtacked?
couldn't you have thumbtacked?
couldn't he have thumbtacked?
couldn't we have thumbtacked?
couldn't you have thumbtacked?
couldn't they have thumbtacked? 	couldn't I have been thumbtacking?
couldn't you have been thumbtacking?
couldn't he have been thumbtacking?
couldn't we have been thumbtacking?
couldn't you have been thumbtacking?
couldn't they have been thumbtacking?