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 cannot lighten you cannot lighten he cannot lighten we cannot lighten you cannot lighten they cannot lighten
V-ing form
I cannot be lightening you cannot be lightening he cannot be lightening we cannot be lightening you cannot be lightening they cannot be lightening
Perfect
I cannot have lightened you cannot have lightened he cannot have lightened we cannot have lightened you cannot have lightened they cannot have lightened
V-ing perfect
I cannot have been lightening you cannot have been lightening he cannot have been lightening we cannot have been lightening you cannot have been lightening they cannot 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 I not lighten? can you not lighten? can he not lighten? can we not lighten? can you not lighten? can they not lighten?
V-ing form
can I not be lightening? can you not be lightening? can he not be lightening? can we not be lightening? can you not be lightening? can they not be lightening?
Perfect
can I not have lightened? can you not have lightened? can he not have lightened? can we not have lightened? can you not have lightened? can they not have lightened?
V-ing perfect
can I not have been lightening? can you not have been lightening? can he not have been lightening? can we not have been lightening? can you not have been lightening? can they not have been lightening?