I can duck you can duck she can duck we can duck you can duck they can duck
V-ing form
I can be ducking you can be ducking she can be ducking we can be ducking you can be ducking they can be ducking
Perfect
I can have ducked you can have ducked she can have ducked we can have ducked you can have ducked they can have ducked
V-ing perfect
I can have been ducking you can have been ducking she can have been ducking we can have been ducking you can have been ducking they can have been ducking
Negation
Simple form
I can't duck you can't duck she can't duck we can't duck you can't duck they can't duck
V-ing form
I can't be ducking you can't be ducking she can't be ducking we can't be ducking you can't be ducking they can't be ducking
Perfect
I can't have ducked you can't have ducked she can't have ducked we can't have ducked you can't have ducked they can't have ducked
V-ing perfect
I can't have been ducking you can't have been ducking she can't have been ducking we can't have been ducking you can't have been ducking they can't have been ducking
Interrogative form
Simple form
can I duck? can you duck? can she duck? can we duck? can you duck? can they duck?
V-ing form
can I be ducking? can you be ducking? can she be ducking? can we be ducking? can you be ducking? can they be ducking?
Perfect
can I have ducked? can you have ducked? can she have ducked? can we have ducked? can you have ducked? can they have ducked?
V-ing perfect
can I have been ducking? can you have been ducking? can she have been ducking? can we have been ducking? can you have been ducking? can they have been ducking?
Interro-negative form
Simple form
can't I duck? can't you duck? can't she duck? can't we duck? can't you duck? can't they duck?
V-ing form
can't I be ducking? can't you be ducking? can't she be ducking? can't we be ducking? can't you be ducking? can't they be ducking?
Perfect
can't I have ducked? can't you have ducked? can't she have ducked? can't we have ducked? can't you have ducked? can't they have ducked?
V-ing perfect
can't I have been ducking? can't you have been ducking? can't she have been ducking? can't we have been ducking? can't you have been ducking? can't they have been ducking?