Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I could knock knock you could knock knock she could knock knock we could knock knock you could knock knock they could knock knock
V-ing form
I could be knock knocking you could be knock knocking she could be knock knocking we could be knock knocking you could be knock knocking they could be knock knocking
Perfect
I could have knock knocked you could have knock knocked she could have knock knocked we could have knock knocked you could have knock knocked they could have knock knocked
V-ing perfect
I could have been knock knocking you could have been knock knocking she could have been knock knocking we could have been knock knocking you could have been knock knocking they could have been knock knocking
Negation
Simple form
I could not knock knock you could not knock knock she could not knock knock we could not knock knock you could not knock knock they could not knock knock
V-ing form
I could not be knock knocking you could not be knock knocking she could not be knock knocking we could not be knock knocking you could not be knock knocking they could not be knock knocking
Perfect
I could not have knock knocked you could not have knock knocked she could not have knock knocked we could not have knock knocked you could not have knock knocked they could not have knock knocked
V-ing perfect
I could not have been knock knocking you could not have been knock knocking she could not have been knock knocking we could not have been knock knocking you could not have been knock knocking they could not have been knock knocking
Interrogative form
Simple form
could I knock knock? could you knock knock? could she knock knock? could we knock knock? could you knock knock? could they knock knock?
V-ing form
could I be knock knocking? could you be knock knocking? could she be knock knocking? could we be knock knocking? could you be knock knocking? could they be knock knocking?
Perfect
could I have knock knocked? could you have knock knocked? could she have knock knocked? could we have knock knocked? could you have knock knocked? could they have knock knocked?
V-ing perfect
could I have been knock knocking? could you have been knock knocking? could she have been knock knocking? could we have been knock knocking? could you have been knock knocking? could they have been knock knocking?
Interro-negative form
Simple form
could I not knock knock? could you not knock knock? could she not knock knock? could we not knock knock? could you not knock knock? could they not knock knock?
V-ing form
could I not be knock knocking? could you not be knock knocking? could she not be knock knocking? could we not be knock knocking? could you not be knock knocking? could they not be knock knocking?
Perfect
could I not have knock knocked? could you not have knock knocked? could she not have knock knocked? could we not have knock knocked? could you not have knock knocked? could they not have knock knocked?
V-ing perfect
could I not have been knock knocking? could you not have been knock knocking? could she not have been knock knocking? could we not have been knock knocking? could you not have been knock knocking? could they not have been knock knocking?