English verb conjugation
COULD TOUGH

Regular verb: tough - toughed - toughed

Affirmation

Simple form	V-ing form
I could tough you could tough he could tough we could tough you could tough they could tough	I could be toughing you could be toughing he could be toughing we could be toughing you could be toughing they could be toughing
Perfect	V-ing perfect
I could have toughed you could have toughed he could have toughed we could have toughed you could have toughed they could have toughed	I could have been toughing you could have been toughing he could have been toughing we could have been toughing you could have been toughing they could have been toughing

Negation

Simple form	V-ing form
I could not tough you could not tough he could not tough we could not tough you could not tough they could not tough	I could not be toughing you could not be toughing he could not be toughing we could not be toughing you could not be toughing they could not be toughing
Perfect	V-ing perfect
I could not have toughed you could not have toughed he could not have toughed we could not have toughed you could not have toughed they could not have toughed	I could not have been toughing you could not have been toughing he could not have been toughing we could not have been toughing you could not have been toughing they could not have been toughing

Interrogative form

Simple form	V-ing form
could I tough? could you tough? could he tough? could we tough? could you tough? could they tough?	could I be toughing? could you be toughing? could he be toughing? could we be toughing? could you be toughing? could they be toughing?
Perfect	V-ing perfect
could I have toughed? could you have toughed? could he have toughed? could we have toughed? could you have toughed? could they have toughed?	could I have been toughing? could you have been toughing? could he have been toughing? could we have been toughing? could you have been toughing? could they have been toughing?

Interro-negative form

Simple form	V-ing form
could I not tough? could you not tough? could he not tough? could we not tough? could you not tough? could they not tough?	could I not be toughing? could you not be toughing? could he not be toughing? could we not be toughing? could you not be toughing? could they not be toughing?
Perfect	V-ing perfect
could I not have toughed? could you not have toughed? could he not have toughed? could we not have toughed? could you not have toughed? could they not have toughed?	could I not have been toughing? could you not have been toughing? could he not have been toughing? could we not have been toughing? could you not have been toughing? could they not have been toughing?