English verb conjugation
COULD QUARTERBACK

Regular verb: quarterback - quarterbacked - quarterbacked

Affirmation

Simple form	V-ing form
I could quarterback you could quarterback he could quarterback we could quarterback you could quarterback they could quarterback	I could be quarterbacking you could be quarterbacking he 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 he 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 he 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 couldn't quarterback you couldn't quarterback he couldn't quarterback we couldn't quarterback you couldn't quarterback they couldn't quarterback	I couldn't be quarterbacking you couldn't be quarterbacking he couldn't be quarterbacking we couldn't be quarterbacking you couldn't be quarterbacking they couldn't be quarterbacking
Perfect	V-ing perfect
I couldn't have quarterbacked you couldn't have quarterbacked he couldn't have quarterbacked we couldn't have quarterbacked you couldn't have quarterbacked they couldn't have quarterbacked	I couldn't have been quarterbacking you couldn't have been quarterbacking he couldn't have been quarterbacking we couldn't have been quarterbacking you couldn't have been quarterbacking they couldn't have been quarterbacking

Interrogative form

Simple form	V-ing form
could I quarterback? could you quarterback? could he quarterback? could we quarterback? could you quarterback? could they quarterback?	could I be quarterbacking? could you be quarterbacking? could he 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 he 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 he 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
couldn't I quarterback? couldn't you quarterback? couldn't he quarterback? couldn't we quarterback? couldn't you quarterback? couldn't they quarterback?	couldn't I be quarterbacking? couldn't you be quarterbacking? couldn't he be quarterbacking? couldn't we be quarterbacking? couldn't you be quarterbacking? couldn't they be quarterbacking?
Perfect	V-ing perfect
couldn't I have quarterbacked? couldn't you have quarterbacked? couldn't he have quarterbacked? couldn't we have quarterbacked? couldn't you have quarterbacked? couldn't they have quarterbacked?	couldn't I have been quarterbacking? couldn't you have been quarterbacking? couldn't he have been quarterbacking? couldn't we have been quarterbacking? couldn't you have been quarterbacking? couldn't they have been quarterbacking?