English verb conjugation
COULD PLANK

Regular verb: plank - planked - planked

Affirmation

Simple form	V-ing form
I could plank you could plank he could plank we could plank you could plank they could plank	I could be planking you could be planking he could be planking we could be planking you could be planking they could be planking
Perfect	V-ing perfect
I could have planked you could have planked he could have planked we could have planked you could have planked they could have planked	I could have been planking you could have been planking he could have been planking we could have been planking you could have been planking they could have been planking

Negation

Simple form	V-ing form
I could not plank you could not plank he could not plank we could not plank you could not plank they could not plank	I could not be planking you could not be planking he could not be planking we could not be planking you could not be planking they could not be planking
Perfect	V-ing perfect
I could not have planked you could not have planked he could not have planked we could not have planked you could not have planked they could not have planked	I could not have been planking you could not have been planking he could not have been planking we could not have been planking you could not have been planking they could not have been planking

Interrogative form

Simple form	V-ing form
could I plank? could you plank? could he plank? could we plank? could you plank? could they plank?	could I be planking? could you be planking? could he be planking? could we be planking? could you be planking? could they be planking?
Perfect	V-ing perfect
could I have planked? could you have planked? could he have planked? could we have planked? could you have planked? could they have planked?	could I have been planking? could you have been planking? could he have been planking? could we have been planking? could you have been planking? could they have been planking?

Interro-negative form

Simple form	V-ing form
could I not plank? could you not plank? could he not plank? could we not plank? could you not plank? could they not plank?	could I not be planking? could you not be planking? could he not be planking? could we not be planking? could you not be planking? could they not be planking?
Perfect	V-ing perfect
could I not have planked? could you not have planked? could he not have planked? could we not have planked? could you not have planked? could they not have planked?	could I not have been planking? could you not have been planking? could he not have been planking? could we not have been planking? could you not have been planking? could they not have been planking?