English verb conjugation
COULD CALCULATE

Regular verb: calculate - calculated - calculated

Affirmation

Simple form	V-ing form
I could calculate you could calculate he could calculate we could calculate you could calculate they could calculate	I could be calculating you could be calculating he could be calculating we could be calculating you could be calculating they could be calculating
Perfect	V-ing perfect
I could have calculated you could have calculated he could have calculated we could have calculated you could have calculated they could have calculated	I could have been calculating you could have been calculating he could have been calculating we could have been calculating you could have been calculating they could have been calculating

Negation

Simple form	V-ing form
I couldn't calculate you couldn't calculate he couldn't calculate we couldn't calculate you couldn't calculate they couldn't calculate	I couldn't be calculating you couldn't be calculating he couldn't be calculating we couldn't be calculating you couldn't be calculating they couldn't be calculating
Perfect	V-ing perfect
I couldn't have calculated you couldn't have calculated he couldn't have calculated we couldn't have calculated you couldn't have calculated they couldn't have calculated	I couldn't have been calculating you couldn't have been calculating he couldn't have been calculating we couldn't have been calculating you couldn't have been calculating they couldn't have been calculating

Interrogative form

Simple form	V-ing form
could I calculate? could you calculate? could he calculate? could we calculate? could you calculate? could they calculate?	could I be calculating? could you be calculating? could he be calculating? could we be calculating? could you be calculating? could they be calculating?
Perfect	V-ing perfect
could I have calculated? could you have calculated? could he have calculated? could we have calculated? could you have calculated? could they have calculated?	could I have been calculating? could you have been calculating? could he have been calculating? could we have been calculating? could you have been calculating? could they have been calculating?

Interro-negative form

Simple form	V-ing form
couldn't I calculate? couldn't you calculate? couldn't he calculate? couldn't we calculate? couldn't you calculate? couldn't they calculate?	couldn't I be calculating? couldn't you be calculating? couldn't he be calculating? couldn't we be calculating? couldn't you be calculating? couldn't they be calculating?
Perfect	V-ing perfect
couldn't I have calculated? couldn't you have calculated? couldn't he have calculated? couldn't we have calculated? couldn't you have calculated? couldn't they have calculated?	couldn't I have been calculating? couldn't you have been calculating? couldn't he have been calculating? couldn't we have been calculating? couldn't you have been calculating? couldn't they have been calculating?