English verb conjugation
COULD QUARTERBACK

Regular verb: quarterback - quarterbacked - quarterbacked

Affirmation

Simple form	V-ing form
I could quarterback you could quarterback she could quarterback we could quarterback you could quarterback they could quarterback	I could be quarterbacking you could be quarterbacking she could be quarterbacking we could be quarterbacking you could be quarterbacking they could be quarterbacking
Perfect	V-ing perfect
I could have quarterbacked you could have quarterbacked she could have quarterbacked we could have quarterbacked you could have quarterbacked they could have quarterbacked	I could have been quarterbacking you could have been quarterbacking she could have been quarterbacking we could have been quarterbacking you could have been quarterbacking they could have been quarterbacking

Negation

Simple form	V-ing form
I could not quarterback you could not quarterback she could not quarterback we could not quarterback you could not quarterback they could not quarterback	I could not be quarterbacking you could not be quarterbacking she could not be quarterbacking we could not be quarterbacking you could not be quarterbacking they could not be quarterbacking
Perfect	V-ing perfect
I could not have quarterbacked you could not have quarterbacked she could not have quarterbacked we could not have quarterbacked you could not have quarterbacked they could not have quarterbacked	I could not have been quarterbacking you could not have been quarterbacking she could not have been quarterbacking we could not have been quarterbacking you could not have been quarterbacking they could not have been quarterbacking

Interrogative form

Simple form	V-ing form
could I quarterback? could you quarterback? could she quarterback? could we quarterback? could you quarterback? could they quarterback?	could I be quarterbacking? could you be quarterbacking? could she be quarterbacking? could we be quarterbacking? could you be quarterbacking? could they be quarterbacking?
Perfect	V-ing perfect
could I have quarterbacked? could you have quarterbacked? could she have quarterbacked? could we have quarterbacked? could you have quarterbacked? could they have quarterbacked?	could I have been quarterbacking? could you have been quarterbacking? could she have been quarterbacking? could we have been quarterbacking? could you have been quarterbacking? could they have been quarterbacking?

Interro-negative form

Simple form	V-ing form
could I not quarterback? could you not quarterback? could she not quarterback? could we not quarterback? could you not quarterback? could they not quarterback?	could I not be quarterbacking? could you not be quarterbacking? could she not be quarterbacking? could we not be quarterbacking? could you not be quarterbacking? could they not be quarterbacking?
Perfect	V-ing perfect
could I not have quarterbacked? could you not have quarterbacked? could she not have quarterbacked? could we not have quarterbacked? could you not have quarterbacked? could they not have quarterbacked?	could I not have been quarterbacking? could you not have been quarterbacking? could she not have been quarterbacking? could we not have been quarterbacking? could you not have been quarterbacking? could they not have been quarterbacking?