English verb conjugation
COULD WINNOW

Regular verb: winnow - winnowed - winnowed

Affirmation

Simple form	V-ing form
I could winnow you could winnow he could winnow we could winnow you could winnow they could winnow	I could be winnowing you could be winnowing he could be winnowing we could be winnowing you could be winnowing they could be winnowing
Perfect	V-ing perfect
I could have winnowed you could have winnowed he could have winnowed we could have winnowed you could have winnowed they could have winnowed	I could have been winnowing you could have been winnowing he could have been winnowing we could have been winnowing you could have been winnowing they could have been winnowing

Negation

Simple form	V-ing form
I could not winnow you could not winnow he could not winnow we could not winnow you could not winnow they could not winnow	I could not be winnowing you could not be winnowing he could not be winnowing we could not be winnowing you could not be winnowing they could not be winnowing
Perfect	V-ing perfect
I could not have winnowed you could not have winnowed he could not have winnowed we could not have winnowed you could not have winnowed they could not have winnowed	I could not have been winnowing you could not have been winnowing he could not have been winnowing we could not have been winnowing you could not have been winnowing they could not have been winnowing

Interrogative form

Simple form	V-ing form
could I winnow? could you winnow? could he winnow? could we winnow? could you winnow? could they winnow?	could I be winnowing? could you be winnowing? could he be winnowing? could we be winnowing? could you be winnowing? could they be winnowing?
Perfect	V-ing perfect
could I have winnowed? could you have winnowed? could he have winnowed? could we have winnowed? could you have winnowed? could they have winnowed?	could I have been winnowing? could you have been winnowing? could he have been winnowing? could we have been winnowing? could you have been winnowing? could they have been winnowing?

Interro-negative form

Simple form	V-ing form
could I not winnow? could you not winnow? could he not winnow? could we not winnow? could you not winnow? could they not winnow?	could I not be winnowing? could you not be winnowing? could he not be winnowing? could we not be winnowing? could you not be winnowing? could they not be winnowing?
Perfect	V-ing perfect
could I not have winnowed? could you not have winnowed? could he not have winnowed? could we not have winnowed? could you not have winnowed? could they not have winnowed?	could I not have been winnowing? could you not have been winnowing? could he not have been winnowing? could we not have been winnowing? could you not have been winnowing? could they not have been winnowing?