English verb conjugation
COULD SIEVE

Regular verb: sieve - sieved - sieved

Affirmation

Simple form	V-ing form
I could sieve you could sieve he could sieve we could sieve you could sieve they could sieve	I could be sieving you could be sieving he could be sieving we could be sieving you could be sieving they could be sieving
Perfect	V-ing perfect
I could have sieved you could have sieved he could have sieved we could have sieved you could have sieved they could have sieved	I could have been sieving you could have been sieving he could have been sieving we could have been sieving you could have been sieving they could have been sieving

Negation

Simple form	V-ing form
I could not sieve you could not sieve he could not sieve we could not sieve you could not sieve they could not sieve	I could not be sieving you could not be sieving he could not be sieving we could not be sieving you could not be sieving they could not be sieving
Perfect	V-ing perfect
I could not have sieved you could not have sieved he could not have sieved we could not have sieved you could not have sieved they could not have sieved	I could not have been sieving you could not have been sieving he could not have been sieving we could not have been sieving you could not have been sieving they could not have been sieving

Interrogative form

Simple form	V-ing form
could I sieve? could you sieve? could he sieve? could we sieve? could you sieve? could they sieve?	could I be sieving? could you be sieving? could he be sieving? could we be sieving? could you be sieving? could they be sieving?
Perfect	V-ing perfect
could I have sieved? could you have sieved? could he have sieved? could we have sieved? could you have sieved? could they have sieved?	could I have been sieving? could you have been sieving? could he have been sieving? could we have been sieving? could you have been sieving? could they have been sieving?

Interro-negative form

Simple form	V-ing form
could I not sieve? could you not sieve? could he not sieve? could we not sieve? could you not sieve? could they not sieve?	could I not be sieving? could you not be sieving? could he not be sieving? could we not be sieving? could you not be sieving? could they not be sieving?
Perfect	V-ing perfect
could I not have sieved? could you not have sieved? could he not have sieved? could we not have sieved? could you not have sieved? could they not have sieved?	could I not have been sieving? could you not have been sieving? could he not have been sieving? could we not have been sieving? could you not have been sieving? could they not have been sieving?