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 couldn't plank you couldn't plank he couldn't plank we couldn't plank you couldn't plank they couldn't plank	I couldn't be planking you couldn't be planking he couldn't be planking we couldn't be planking you couldn't be planking they couldn't be planking
Perfect	V-ing perfect
I couldn't have planked you couldn't have planked he couldn't have planked we couldn't have planked you couldn't have planked they couldn't have planked	I couldn't have been planking you couldn't have been planking he couldn't have been planking we couldn't have been planking you couldn't have been planking they couldn't 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
couldn't I plank? couldn't you plank? couldn't he plank? couldn't we plank? couldn't you plank? couldn't they plank?	couldn't I be planking? couldn't you be planking? couldn't he be planking? couldn't we be planking? couldn't you be planking? couldn't they be planking?
Perfect	V-ing perfect
couldn't I have planked? couldn't you have planked? couldn't he have planked? couldn't we have planked? couldn't you have planked? couldn't they have planked?	couldn't I have been planking? couldn't you have been planking? couldn't he have been planking? couldn't we have been planking? couldn't you have been planking? couldn't they have been planking?