I can sleep you can sleep she can sleep we can sleep you can sleep they can sleep
V-ing form
I can be sleeping you can be sleeping she can be sleeping we can be sleeping you can be sleeping they can be sleeping
Perfect
I can have slept you can have slept she can have slept we can have slept you can have slept they can have slept
V-ing perfect
I can have been sleeping you can have been sleeping she can have been sleeping we can have been sleeping you can have been sleeping they can have been sleeping
Negation
Simple form
I can't sleep you can't sleep she can't sleep we can't sleep you can't sleep they can't sleep
V-ing form
I can't be sleeping you can't be sleeping she can't be sleeping we can't be sleeping you can't be sleeping they can't be sleeping
Perfect
I can't have slept you can't have slept she can't have slept we can't have slept you can't have slept they can't have slept
V-ing perfect
I can't have been sleeping you can't have been sleeping she can't have been sleeping we can't have been sleeping you can't have been sleeping they can't have been sleeping
Interrogative form
Simple form
can I sleep? can you sleep? can she sleep? can we sleep? can you sleep? can they sleep?
V-ing form
can I be sleeping? can you be sleeping? can she be sleeping? can we be sleeping? can you be sleeping? can they be sleeping?
Perfect
can I have slept? can you have slept? can she have slept? can we have slept? can you have slept? can they have slept?
V-ing perfect
can I have been sleeping? can you have been sleeping? can she have been sleeping? can we have been sleeping? can you have been sleeping? can they have been sleeping?
Interro-negative form
Simple form
can't I sleep? can't you sleep? can't she sleep? can't we sleep? can't you sleep? can't they sleep?
V-ing form
can't I be sleeping? can't you be sleeping? can't she be sleeping? can't we be sleeping? can't you be sleeping? can't they be sleeping?
Perfect
can't I have slept? can't you have slept? can't she have slept? can't we have slept? can't you have slept? can't they have slept?
V-ing perfect
can't I have been sleeping? can't you have been sleeping? can't she have been sleeping? can't we have been sleeping? can't you have been sleeping? can't they have been sleeping?