English verb conjugation
COULD SUFFIX

Regular verb: suffix - suffixed - suffixed

Affirmation

Simple form	V-ing form
I could suffix you could suffix he could suffix we could suffix you could suffix they could suffix	I could be suffixing you could be suffixing he could be suffixing we could be suffixing you could be suffixing they could be suffixing
Perfect	V-ing perfect
I could have suffixed you could have suffixed he could have suffixed we could have suffixed you could have suffixed they could have suffixed	I could have been suffixing you could have been suffixing he could have been suffixing we could have been suffixing you could have been suffixing they could have been suffixing

Negation

Simple form	V-ing form
I could not suffix you could not suffix he could not suffix we could not suffix you could not suffix they could not suffix	I could not be suffixing you could not be suffixing he could not be suffixing we could not be suffixing you could not be suffixing they could not be suffixing
Perfect	V-ing perfect
I could not have suffixed you could not have suffixed he could not have suffixed we could not have suffixed you could not have suffixed they could not have suffixed	I could not have been suffixing you could not have been suffixing he could not have been suffixing we could not have been suffixing you could not have been suffixing they could not have been suffixing

Interrogative form

Simple form	V-ing form
could I suffix? could you suffix? could he suffix? could we suffix? could you suffix? could they suffix?	could I be suffixing? could you be suffixing? could he be suffixing? could we be suffixing? could you be suffixing? could they be suffixing?
Perfect	V-ing perfect
could I have suffixed? could you have suffixed? could he have suffixed? could we have suffixed? could you have suffixed? could they have suffixed?	could I have been suffixing? could you have been suffixing? could he have been suffixing? could we have been suffixing? could you have been suffixing? could they have been suffixing?

Interro-negative form

Simple form	V-ing form
could I not suffix? could you not suffix? could he not suffix? could we not suffix? could you not suffix? could they not suffix?	could I not be suffixing? could you not be suffixing? could he not be suffixing? could we not be suffixing? could you not be suffixing? could they not be suffixing?
Perfect	V-ing perfect
could I not have suffixed? could you not have suffixed? could he not have suffixed? could we not have suffixed? could you not have suffixed? could they not have suffixed?	could I not have been suffixing? could you not have been suffixing? could he not have been suffixing? could we not have been suffixing? could you not have been suffixing? could they not have been suffixing?