I can fork you can fork he can fork we can fork you can fork they can fork
V-ing form
I can be forking you can be forking he can be forking we can be forking you can be forking they can be forking
Perfect
I can have forked you can have forked he can have forked we can have forked you can have forked they can have forked
V-ing perfect
I can have been forking you can have been forking he can have been forking we can have been forking you can have been forking they can have been forking
Negation
Simple form
I can't fork you can't fork he can't fork we can't fork you can't fork they can't fork
V-ing form
I can't be forking you can't be forking he can't be forking we can't be forking you can't be forking they can't be forking
Perfect
I can't have forked you can't have forked he can't have forked we can't have forked you can't have forked they can't have forked
V-ing perfect
I can't have been forking you can't have been forking he can't have been forking we can't have been forking you can't have been forking they can't have been forking
Interrogative form
Simple form
can I fork? can you fork? can he fork? can we fork? can you fork? can they fork?
V-ing form
can I be forking? can you be forking? can he be forking? can we be forking? can you be forking? can they be forking?
Perfect
can I have forked? can you have forked? can he have forked? can we have forked? can you have forked? can they have forked?
V-ing perfect
can I have been forking? can you have been forking? can he have been forking? can we have been forking? can you have been forking? can they have been forking?
Interro-negative form
Simple form
can't I fork? can't you fork? can't he fork? can't we fork? can't you fork? can't they fork?
V-ing form
can't I be forking? can't you be forking? can't he be forking? can't we be forking? can't you be forking? can't they be forking?
Perfect
can't I have forked? can't you have forked? can't he have forked? can't we have forked? can't you have forked? can't they have forked?
V-ing perfect
can't I have been forking? can't you have been forking? can't he have been forking? can't we have been forking? can't you have been forking? can't they have been forking?