could toughen
Verbe régulier : toughen - toughened- toughened
Traduction française : rendre plus solide - durcir 

Affirmation 	
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I could toughen
you could toughen
he could toughen
we could toughen
you could toughen
they could toughen 	I could be toughening
you could be toughening
he could be toughening
we could be toughening
you could be toughening
they could be toughening	I could have toughened
you could have toughened
he could have toughened
we could have toughened
you could have toughened
they could have toughened	I could have been toughening
you could have been toughening
he could have been toughening
we could have been toughening
you could have been toughening
they could have been toughening	

Négation 	
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I could not toughen
you could not toughen
he could not toughen
we could not toughen
you could not toughen
they could not toughen 	I could not be toughening
you could not be toughening
he could not be toughening
we could not be toughening
you could not be toughening
they could not be toughening	I could not have toughened
you could not have toughened
he could not have toughened
we could not have toughened
you could not have toughened
they could not have toughened	I could not have been toughening
you could not have been toughening
he could not have been toughening
we could not have been toughening
you could not have been toughening
they could not have been toughening	

Forme interrogative 	
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could I toughen?
could you toughen?
could he toughen?
could we toughen?
could you toughen?
could they toughen? 	could I be toughening?
could you be toughening?
could he be toughening?
could we be toughening?
could you be toughening?
could they be toughening? 	could I have toughened?
could you have toughened?
could he have toughened?
could we have toughened?
could you have toughened?
could they have toughened? 	could I have been toughening?
could you have been toughening?
could he have been toughening?
could we have been toughening?
could you have been toughening?
could they have been toughening? 	

Forme interro-négative 	
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could I not toughen?
could you not toughen?
could he not toughen?
could we not toughen?
could you not toughen?
could they not toughen? 	could I not be toughening?
could you not be toughening?
could he not be toughening?
could we not be toughening?
could you not be toughening?
could they not be toughening? 	could I not have toughened?
could you not have toughened?
could he not have toughened?
could we not have toughened?
could you not have toughened?
could they not have toughened? 	could I not have been toughening?
could you not have been toughening?
could he not have been toughening?
could we not have been toughening?
could you not have been toughening?
could they not have been toughening?