English verb conjugation
COULD CURVE

Regular verb: curve - curved - curved

Affirmation

Simple form	V-ing form
I could curve you could curve he could curve we could curve you could curve they could curve	I could be curving you could be curving he could be curving we could be curving you could be curving they could be curving
Perfect	V-ing perfect
I could have curved you could have curved he could have curved we could have curved you could have curved they could have curved	I could have been curving you could have been curving he could have been curving we could have been curving you could have been curving they could have been curving

Negation

Simple form	V-ing form
I could not curve you could not curve he could not curve we could not curve you could not curve they could not curve	I could not be curving you could not be curving he could not be curving we could not be curving you could not be curving they could not be curving
Perfect	V-ing perfect
I could not have curved you could not have curved he could not have curved we could not have curved you could not have curved they could not have curved	I could not have been curving you could not have been curving he could not have been curving we could not have been curving you could not have been curving they could not have been curving

Interrogative form

Simple form	V-ing form
could I curve? could you curve? could he curve? could we curve? could you curve? could they curve?	could I be curving? could you be curving? could he be curving? could we be curving? could you be curving? could they be curving?
Perfect	V-ing perfect
could I have curved? could you have curved? could he have curved? could we have curved? could you have curved? could they have curved?	could I have been curving? could you have been curving? could he have been curving? could we have been curving? could you have been curving? could they have been curving?

Interro-negative form

Simple form	V-ing form
could I not curve? could you not curve? could he not curve? could we not curve? could you not curve? could they not curve?	could I not be curving? could you not be curving? could he not be curving? could we not be curving? could you not be curving? could they not be curving?
Perfect	V-ing perfect
could I not have curved? could you not have curved? could he not have curved? could we not have curved? could you not have curved? could they not have curved?	could I not have been curving? could you not have been curving? could he not have been curving? could we not have been curving? could you not have been curving? could they not have been curving?