Conjugación del verbo inglés
COULD TOUGHEN

Verbo regular: toughen - toughened - toughened

Afirmación

Forma simple	Forma con V-ing
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
Perfecto	Perfecto con V-ing
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

Negación

Forma simple	Forma con V-ing
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
Perfecto	Perfecto con V-ing
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

Forma interrogativa

Forma simple	Forma con V-ing
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?
Perfecto	Perfecto con V-ing
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?

Forma interro-negativa

Forma simple	Forma con V-ing
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?
Perfecto	Perfecto con V-ing
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?