I can shorten you can shorten he can shorten we can shorten you can shorten they can shorten
V-ing form
I can be shortening you can be shortening he can be shortening we can be shortening you can be shortening they can be shortening
Perfect
I can have shortened you can have shortened he can have shortened we can have shortened you can have shortened they can have shortened
V-ing perfect
I can have been shortening you can have been shortening he can have been shortening we can have been shortening you can have been shortening they can have been shortening
Negation
Simple form
I can't shorten you can't shorten he can't shorten we can't shorten you can't shorten they can't shorten
V-ing form
I can't be shortening you can't be shortening he can't be shortening we can't be shortening you can't be shortening they can't be shortening
Perfect
I can't have shortened you can't have shortened he can't have shortened we can't have shortened you can't have shortened they can't have shortened
V-ing perfect
I can't have been shortening you can't have been shortening he can't have been shortening we can't have been shortening you can't have been shortening they can't have been shortening
Interrogative form
Simple form
can I shorten? can you shorten? can he shorten? can we shorten? can you shorten? can they shorten?
V-ing form
can I be shortening? can you be shortening? can he be shortening? can we be shortening? can you be shortening? can they be shortening?
Perfect
can I have shortened? can you have shortened? can he have shortened? can we have shortened? can you have shortened? can they have shortened?
V-ing perfect
can I have been shortening? can you have been shortening? can he have been shortening? can we have been shortening? can you have been shortening? can they have been shortening?
Interro-negative form
Simple form
can't I shorten? can't you shorten? can't he shorten? can't we shorten? can't you shorten? can't they shorten?
V-ing form
can't I be shortening? can't you be shortening? can't he be shortening? can't we be shortening? can't you be shortening? can't they be shortening?
Perfect
can't I have shortened? can't you have shortened? can't he have shortened? can't we have shortened? can't you have shortened? can't they have shortened?
V-ing perfect
can't I have been shortening? can't you have been shortening? can't he have been shortening? can't we have been shortening? can't you have been shortening? can't they have been shortening?