English verb conjugation
COULD ZERO

Regular verb: zero - zeroed - zeroed

Affirmation

Simple form	V-ing form
I could zero you could zero she could zero we could zero you could zero they could zero	I could be zeroing you could be zeroing she could be zeroing we could be zeroing you could be zeroing they could be zeroing
Perfect	V-ing perfect
I could have zeroed you could have zeroed she could have zeroed we could have zeroed you could have zeroed they could have zeroed	I could have been zeroing you could have been zeroing she could have been zeroing we could have been zeroing you could have been zeroing they could have been zeroing

Negation

Simple form	V-ing form
I couldn't zero you couldn't zero she couldn't zero we couldn't zero you couldn't zero they couldn't zero	I couldn't be zeroing you couldn't be zeroing she couldn't be zeroing we couldn't be zeroing you couldn't be zeroing they couldn't be zeroing
Perfect	V-ing perfect
I couldn't have zeroed you couldn't have zeroed she couldn't have zeroed we couldn't have zeroed you couldn't have zeroed they couldn't have zeroed	I couldn't have been zeroing you couldn't have been zeroing she couldn't have been zeroing we couldn't have been zeroing you couldn't have been zeroing they couldn't have been zeroing

Interrogative form

Simple form	V-ing form
could I zero? could you zero? could she zero? could we zero? could you zero? could they zero?	could I be zeroing? could you be zeroing? could she be zeroing? could we be zeroing? could you be zeroing? could they be zeroing?
Perfect	V-ing perfect
could I have zeroed? could you have zeroed? could she have zeroed? could we have zeroed? could you have zeroed? could they have zeroed?	could I have been zeroing? could you have been zeroing? could she have been zeroing? could we have been zeroing? could you have been zeroing? could they have been zeroing?

Interro-negative form

Simple form	V-ing form
couldn't I zero? couldn't you zero? couldn't she zero? couldn't we zero? couldn't you zero? couldn't they zero?	couldn't I be zeroing? couldn't you be zeroing? couldn't she be zeroing? couldn't we be zeroing? couldn't you be zeroing? couldn't they be zeroing?
Perfect	V-ing perfect
couldn't I have zeroed? couldn't you have zeroed? couldn't she have zeroed? couldn't we have zeroed? couldn't you have zeroed? couldn't they have zeroed?	couldn't I have been zeroing? couldn't you have been zeroing? couldn't she have been zeroing? couldn't we have been zeroing? couldn't you have been zeroing? couldn't they have been zeroing?