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 couldn't duck you couldn't duck he couldn't duck we couldn't duck you couldn't duck they couldn't duck	I couldn't be ducking you couldn't be ducking he couldn't be ducking we couldn't be ducking you couldn't be ducking they couldn't be ducking
Perfect	V-ing perfect
I couldn't have ducked you couldn't have ducked he couldn't have ducked we couldn't have ducked you couldn't have ducked they couldn't have ducked	I couldn't have been ducking you couldn't have been ducking he couldn't have been ducking we couldn't have been ducking you couldn't have been ducking they couldn't 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
couldn't I duck? couldn't you duck? couldn't he duck? couldn't we duck? couldn't you duck? couldn't they duck?	couldn't I be ducking? couldn't you be ducking? couldn't he be ducking? couldn't we be ducking? couldn't you be ducking? couldn't they be ducking?
Perfect	V-ing perfect
couldn't I have ducked? couldn't you have ducked? couldn't he have ducked? couldn't we have ducked? couldn't you have ducked? couldn't they have ducked?	couldn't I have been ducking? couldn't you have been ducking? couldn't he have been ducking? couldn't we have been ducking? couldn't you have been ducking? couldn't they have been ducking?