English verb conjugation
COULD DERIVE

Regular verb: derive - derived - derived

Affirmation

Simple form	V-ing form
I could derive you could derive he could derive we could derive you could derive they could derive	I could be deriving you could be deriving he could be deriving we could be deriving you could be deriving they could be deriving
Perfect	V-ing perfect
I could have derived you could have derived he could have derived we could have derived you could have derived they could have derived	I could have been deriving you could have been deriving he could have been deriving we could have been deriving you could have been deriving they could have been deriving

Negation

Simple form	V-ing form
I couldn't derive you couldn't derive he couldn't derive we couldn't derive you couldn't derive they couldn't derive	I couldn't be deriving you couldn't be deriving he couldn't be deriving we couldn't be deriving you couldn't be deriving they couldn't be deriving
Perfect	V-ing perfect
I couldn't have derived you couldn't have derived he couldn't have derived we couldn't have derived you couldn't have derived they couldn't have derived	I couldn't have been deriving you couldn't have been deriving he couldn't have been deriving we couldn't have been deriving you couldn't have been deriving they couldn't have been deriving

Interrogative form

Simple form	V-ing form
could I derive? could you derive? could he derive? could we derive? could you derive? could they derive?	could I be deriving? could you be deriving? could he be deriving? could we be deriving? could you be deriving? could they be deriving?
Perfect	V-ing perfect
could I have derived? could you have derived? could he have derived? could we have derived? could you have derived? could they have derived?	could I have been deriving? could you have been deriving? could he have been deriving? could we have been deriving? could you have been deriving? could they have been deriving?

Interro-negative form

Simple form	V-ing form
couldn't I derive? couldn't you derive? couldn't he derive? couldn't we derive? couldn't you derive? couldn't they derive?	couldn't I be deriving? couldn't you be deriving? couldn't he be deriving? couldn't we be deriving? couldn't you be deriving? couldn't they be deriving?
Perfect	V-ing perfect
couldn't I have derived? couldn't you have derived? couldn't he have derived? couldn't we have derived? couldn't you have derived? couldn't they have derived?	couldn't I have been deriving? couldn't you have been deriving? couldn't he have been deriving? couldn't we have been deriving? couldn't you have been deriving? couldn't they have been deriving?