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 couldn't tough you couldn't tough he couldn't tough we couldn't tough you couldn't tough they couldn't tough	I couldn't be toughing you couldn't be toughing he couldn't be toughing we couldn't be toughing you couldn't be toughing they couldn't be toughing
Perfect	V-ing perfect
I couldn't have toughed you couldn't have toughed he couldn't have toughed we couldn't have toughed you couldn't have toughed they couldn't have toughed	I couldn't have been toughing you couldn't have been toughing he couldn't have been toughing we couldn't have been toughing you couldn't have been toughing they couldn't 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
couldn't I tough? couldn't you tough? couldn't he tough? couldn't we tough? couldn't you tough? couldn't they tough?	couldn't I be toughing? couldn't you be toughing? couldn't he be toughing? couldn't we be toughing? couldn't you be toughing? couldn't they be toughing?
Perfect	V-ing perfect
couldn't I have toughed? couldn't you have toughed? couldn't he have toughed? couldn't we have toughed? couldn't you have toughed? couldn't they have toughed?	couldn't I have been toughing? couldn't you have been toughing? couldn't he have been toughing? couldn't we have been toughing? couldn't you have been toughing? couldn't they have been toughing?