English verb conjugation
MUST SHARPEN

Regular verb: sharpen - sharpened - sharpened

Affirmation

Simple form	V-ing form
I must sharpen you must sharpen she must sharpen we must sharpen you must sharpen they must sharpen	I must be sharpening you must be sharpening she must be sharpening we must be sharpening you must be sharpening they must be sharpening
Perfect	V-ing perfect
I must have sharpened you must have sharpened she must have sharpened we must have sharpened you must have sharpened they must have sharpened	I must have been sharpening you must have been sharpening she must have been sharpening we must have been sharpening you must have been sharpening they must have been sharpening

Negation

Simple form	V-ing form
I must not sharpen you must not sharpen she must not sharpen we must not sharpen you must not sharpen they must not sharpen	I must not be sharpening you must not be sharpening she must not be sharpening we must not be sharpening you must not be sharpening they must not be sharpening
Perfect	V-ing perfect
I must not have sharpened you must not have sharpened she must not have sharpened we must not have sharpened you must not have sharpened they must not have sharpened	I must not have been sharpening you must not have been sharpening she must not have been sharpening we must not have been sharpening you must not have been sharpening they must not have been sharpening

Interrogative form

Simple form	V-ing form
must I sharpen? must you sharpen? must she sharpen? must we sharpen? must you sharpen? must they sharpen?	must I be sharpening? must you be sharpening? must she be sharpening? must we be sharpening? must you be sharpening? must they be sharpening?
Perfect	V-ing perfect
must I have sharpened? must you have sharpened? must she have sharpened? must we have sharpened? must you have sharpened? must they have sharpened?	must I have been sharpening? must you have been sharpening? must she have been sharpening? must we have been sharpening? must you have been sharpening? must they have been sharpening?

Interro-negative form

Simple form	V-ing form
must I not sharpen? must you not sharpen? must she not sharpen? must we not sharpen? must you not sharpen? must they not sharpen?	must I not be sharpening? must you not be sharpening? must she not be sharpening? must we not be sharpening? must you not be sharpening? must they not be sharpening?
Perfect	V-ing perfect
must I not have sharpened? must you not have sharpened? must she not have sharpened? must we not have sharpened? must you not have sharpened? must they not have sharpened?	must I not have been sharpening? must you not have been sharpening? must she not have been sharpening? must we not have been sharpening? must you not have been sharpening? must they not have been sharpening?