must sharpen
Regular verb: sharpen - sharpened- sharpened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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	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 	Perfect 	V-ing perfect 	
I mustn't sharpen
you mustn't sharpen
she mustn't sharpen
we mustn't sharpen
you mustn't sharpen
they mustn't sharpen 	I mustn't be sharpening
you mustn't be sharpening
she mustn't be sharpening
we mustn't be sharpening
you mustn't be sharpening
they mustn't be sharpening	I mustn't have sharpened
you mustn't have sharpened
she mustn't have sharpened
we mustn't have sharpened
you mustn't have sharpened
they mustn't have sharpened	I mustn't have been sharpening
you mustn't have been sharpening
she mustn't have been sharpening
we mustn't have been sharpening
you mustn't have been sharpening
they mustn't have been sharpening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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? 	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 	Perfect 	V-ing perfect 	
mustn't I sharpen?
mustn't you sharpen?
mustn't she sharpen?
mustn't we sharpen?
mustn't you sharpen?
mustn't they sharpen? 	mustn't I be sharpening?
mustn't you be sharpening?
mustn't she be sharpening?
mustn't we be sharpening?
mustn't you be sharpening?
mustn't they be sharpening? 	mustn't I have sharpened?
mustn't you have sharpened?
mustn't she have sharpened?
mustn't we have sharpened?
mustn't you have sharpened?
mustn't they have sharpened? 	mustn't I have been sharpening?
mustn't you have been sharpening?
mustn't she have been sharpening?
mustn't we have been sharpening?
mustn't you have been sharpening?
mustn't they have been sharpening?