English verb conjugation
COULD DUCK

Regular verb: duck - ducked - ducked

Affirmation

Simple form	V-ing form
I could duck you could duck he could duck we could duck you could duck they could duck	I could be ducking you could be ducking he could be ducking we could be ducking you could be ducking they could be ducking
Perfect	V-ing perfect
I could have ducked you could have ducked he could have ducked we could have ducked you could have ducked they could have ducked	I could have been ducking you could have been ducking he could have been ducking we could have been ducking you could have been ducking they could have been ducking

Negation

Simple form	V-ing form
I could not duck you could not duck he could not duck we could not duck you could not duck they could not duck	I could not be ducking you could not be ducking he could not be ducking we could not be ducking you could not be ducking they could not be ducking
Perfect	V-ing perfect
I could not have ducked you could not have ducked he could not have ducked we could not have ducked you could not have ducked they could not have ducked	I could not have been ducking you could not have been ducking he could not have been ducking we could not have been ducking you could not have been ducking they could not have been ducking

Interrogative form

Simple form	V-ing form
could I duck? could you duck? could he duck? could we duck? could you duck? could they duck?	could I be ducking? could you be ducking? could he be ducking? could we be ducking? could you be ducking? could they be ducking?
Perfect	V-ing perfect
could I have ducked? could you have ducked? could he have ducked? could we have ducked? could you have ducked? could they have ducked?	could I have been ducking? could you have been ducking? could he have been ducking? could we have been ducking? could you have been ducking? could they have been ducking?

Interro-negative form

Simple form	V-ing form
could I not duck? could you not duck? could he not duck? could we not duck? could you not duck? could they not duck?	could I not be ducking? could you not be ducking? could he not be ducking? could we not be ducking? could you not be ducking? could they not be ducking?
Perfect	V-ing perfect
could I not have ducked? could you not have ducked? could he not have ducked? could we not have ducked? could you not have ducked? could they not have ducked?	could I not have been ducking? could you not have been ducking? could he not have been ducking? could we not have been ducking? could you not have been ducking? could they not have been ducking?