I can lighten you can lighten he can lighten we can lighten you can lighten they can lighten
V-ing form
I can be lightening you can be lightening he can be lightening we can be lightening you can be lightening they can be lightening
Perfect
I can have lightened you can have lightened he can have lightened we can have lightened you can have lightened they can have lightened
V-ing perfect
I can have been lightening you can have been lightening he can have been lightening we can have been lightening you can have been lightening they can have been lightening
Negation
Simple form
I can't lighten you can't lighten he can't lighten we can't lighten you can't lighten they can't lighten
V-ing form
I can't be lightening you can't be lightening he can't be lightening we can't be lightening you can't be lightening they can't be lightening
Perfect
I can't have lightened you can't have lightened he can't have lightened we can't have lightened you can't have lightened they can't have lightened
V-ing perfect
I can't have been lightening you can't have been lightening he can't have been lightening we can't have been lightening you can't have been lightening they can't have been lightening
Interrogative form
Simple form
can I lighten? can you lighten? can he lighten? can we lighten? can you lighten? can they lighten?
V-ing form
can I be lightening? can you be lightening? can he be lightening? can we be lightening? can you be lightening? can they be lightening?
Perfect
can I have lightened? can you have lightened? can he have lightened? can we have lightened? can you have lightened? can they have lightened?
V-ing perfect
can I have been lightening? can you have been lightening? can he have been lightening? can we have been lightening? can you have been lightening? can they have been lightening?
Interro-negative form
Simple form
can't I lighten? can't you lighten? can't he lighten? can't we lighten? can't you lighten? can't they lighten?
V-ing form
can't I be lightening? can't you be lightening? can't he be lightening? can't we be lightening? can't you be lightening? can't they be lightening?
Perfect
can't I have lightened? can't you have lightened? can't he have lightened? can't we have lightened? can't you have lightened? can't they have lightened?
V-ing perfect
can't I have been lightening? can't you have been lightening? can't he have been lightening? can't we have been lightening? can't you have been lightening? can't they have been lightening?