I can sharpen you can sharpen she can sharpen we can sharpen you can sharpen they can sharpen
V-ing form
I can be sharpening you can be sharpening she can be sharpening we can be sharpening you can be sharpening they can be sharpening
Perfect
I can have sharpened you can have sharpened she can have sharpened we can have sharpened you can have sharpened they can have sharpened
V-ing perfect
I can have been sharpening you can have been sharpening she can have been sharpening we can have been sharpening you can have been sharpening they can have been sharpening
Negation
Simple form
I cannot sharpen you cannot sharpen she cannot sharpen we cannot sharpen you cannot sharpen they cannot sharpen
V-ing form
I cannot be sharpening you cannot be sharpening she cannot be sharpening we cannot be sharpening you cannot be sharpening they cannot be sharpening
Perfect
I cannot have sharpened you cannot have sharpened she cannot have sharpened we cannot have sharpened you cannot have sharpened they cannot have sharpened
V-ing perfect
I cannot have been sharpening you cannot have been sharpening she cannot have been sharpening we cannot have been sharpening you cannot have been sharpening they cannot have been sharpening
Interrogative form
Simple form
can I sharpen? can you sharpen? can she sharpen? can we sharpen? can you sharpen? can they sharpen?
V-ing form
can I be sharpening? can you be sharpening? can she be sharpening? can we be sharpening? can you be sharpening? can they be sharpening?
Perfect
can I have sharpened? can you have sharpened? can she have sharpened? can we have sharpened? can you have sharpened? can they have sharpened?
V-ing perfect
can I have been sharpening? can you have been sharpening? can she have been sharpening? can we have been sharpening? can you have been sharpening? can they have been sharpening?
Interro-negative form
Simple form
can I not sharpen? can you not sharpen? can she not sharpen? can we not sharpen? can you not sharpen? can they not sharpen?
V-ing form
can I not be sharpening? can you not be sharpening? can she not be sharpening? can we not be sharpening? can you not be sharpening? can they not be sharpening?
Perfect
can I not have sharpened? can you not have sharpened? can she not have sharpened? can we not have sharpened? can you not have sharpened? can they not have sharpened?
V-ing perfect
can I not have been sharpening? can you not have been sharpening? can she not have been sharpening? can we not have been sharpening? can you not have been sharpening? can they not have been sharpening?