I can darken you can darken she can darken we can darken you can darken they can darken
V-ing form
I can be darkening you can be darkening she can be darkening we can be darkening you can be darkening they can be darkening
Perfect
I can have darkened you can have darkened she can have darkened we can have darkened you can have darkened they can have darkened
V-ing perfect
I can have been darkening you can have been darkening she can have been darkening we can have been darkening you can have been darkening they can have been darkening
Negation
Simple form
I cannot darken you cannot darken she cannot darken we cannot darken you cannot darken they cannot darken
V-ing form
I cannot be darkening you cannot be darkening she cannot be darkening we cannot be darkening you cannot be darkening they cannot be darkening
Perfect
I cannot have darkened you cannot have darkened she cannot have darkened we cannot have darkened you cannot have darkened they cannot have darkened
V-ing perfect
I cannot have been darkening you cannot have been darkening she cannot have been darkening we cannot have been darkening you cannot have been darkening they cannot have been darkening
Interrogative form
Simple form
can I darken? can you darken? can she darken? can we darken? can you darken? can they darken?
V-ing form
can I be darkening? can you be darkening? can she be darkening? can we be darkening? can you be darkening? can they be darkening?
Perfect
can I have darkened? can you have darkened? can she have darkened? can we have darkened? can you have darkened? can they have darkened?
V-ing perfect
can I have been darkening? can you have been darkening? can she have been darkening? can we have been darkening? can you have been darkening? can they have been darkening?
Interro-negative form
Simple form
can I not darken? can you not darken? can she not darken? can we not darken? can you not darken? can they not darken?
V-ing form
can I not be darkening? can you not be darkening? can she not be darkening? can we not be darkening? can you not be darkening? can they not be darkening?
Perfect
can I not have darkened? can you not have darkened? can she not have darkened? can we not have darkened? can you not have darkened? can they not have darkened?
V-ing perfect
can I not have been darkening? can you not have been darkening? can she not have been darkening? can we not have been darkening? can you not have been darkening? can they not have been darkening?