English verb conjugation
COULD POSTFIX

Regular verb: postfix - postfixed - postfixed

Affirmation

Simple form	V-ing form
I could postfix you could postfix she could postfix we could postfix you could postfix they could postfix	I could be postfixing you could be postfixing she could be postfixing we could be postfixing you could be postfixing they could be postfixing
Perfect	V-ing perfect
I could have postfixed you could have postfixed she could have postfixed we could have postfixed you could have postfixed they could have postfixed	I could have been postfixing you could have been postfixing she could have been postfixing we could have been postfixing you could have been postfixing they could have been postfixing

Negation

Simple form	V-ing form
I couldn't postfix you couldn't postfix she couldn't postfix we couldn't postfix you couldn't postfix they couldn't postfix	I couldn't be postfixing you couldn't be postfixing she couldn't be postfixing we couldn't be postfixing you couldn't be postfixing they couldn't be postfixing
Perfect	V-ing perfect
I couldn't have postfixed you couldn't have postfixed she couldn't have postfixed we couldn't have postfixed you couldn't have postfixed they couldn't have postfixed	I couldn't have been postfixing you couldn't have been postfixing she couldn't have been postfixing we couldn't have been postfixing you couldn't have been postfixing they couldn't have been postfixing

Interrogative form

Simple form	V-ing form
could I postfix? could you postfix? could she postfix? could we postfix? could you postfix? could they postfix?	could I be postfixing? could you be postfixing? could she be postfixing? could we be postfixing? could you be postfixing? could they be postfixing?
Perfect	V-ing perfect
could I have postfixed? could you have postfixed? could she have postfixed? could we have postfixed? could you have postfixed? could they have postfixed?	could I have been postfixing? could you have been postfixing? could she have been postfixing? could we have been postfixing? could you have been postfixing? could they have been postfixing?

Interro-negative form

Simple form	V-ing form
couldn't I postfix? couldn't you postfix? couldn't she postfix? couldn't we postfix? couldn't you postfix? couldn't they postfix?	couldn't I be postfixing? couldn't you be postfixing? couldn't she be postfixing? couldn't we be postfixing? couldn't you be postfixing? couldn't they be postfixing?
Perfect	V-ing perfect
couldn't I have postfixed? couldn't you have postfixed? couldn't she have postfixed? couldn't we have postfixed? couldn't you have postfixed? couldn't they have postfixed?	couldn't I have been postfixing? couldn't you have been postfixing? couldn't she have been postfixing? couldn't we have been postfixing? couldn't you have been postfixing? couldn't they have been postfixing?