must unscrew
Regular verb: unscrew - unscrewed- unscrewed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must unscrew
you must unscrew
he must unscrew
we must unscrew
you must unscrew
they must unscrew 	I must be unscrewing
you must be unscrewing
he must be unscrewing
we must be unscrewing
you must be unscrewing
they must be unscrewing	I must have unscrewed
you must have unscrewed
he must have unscrewed
we must have unscrewed
you must have unscrewed
they must have unscrewed	I must have been unscrewing
you must have been unscrewing
he must have been unscrewing
we must have been unscrewing
you must have been unscrewing
they must have been unscrewing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't unscrew
you mustn't unscrew
he mustn't unscrew
we mustn't unscrew
you mustn't unscrew
they mustn't unscrew 	I mustn't be unscrewing
you mustn't be unscrewing
he mustn't be unscrewing
we mustn't be unscrewing
you mustn't be unscrewing
they mustn't be unscrewing	I mustn't have unscrewed
you mustn't have unscrewed
he mustn't have unscrewed
we mustn't have unscrewed
you mustn't have unscrewed
they mustn't have unscrewed	I mustn't have been unscrewing
you mustn't have been unscrewing
he mustn't have been unscrewing
we mustn't have been unscrewing
you mustn't have been unscrewing
they mustn't have been unscrewing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I unscrew?
must you unscrew?
must he unscrew?
must we unscrew?
must you unscrew?
must they unscrew? 	must I be unscrewing?
must you be unscrewing?
must he be unscrewing?
must we be unscrewing?
must you be unscrewing?
must they be unscrewing? 	must I have unscrewed?
must you have unscrewed?
must he have unscrewed?
must we have unscrewed?
must you have unscrewed?
must they have unscrewed? 	must I have been unscrewing?
must you have been unscrewing?
must he have been unscrewing?
must we have been unscrewing?
must you have been unscrewing?
must they have been unscrewing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I unscrew?
mustn't you unscrew?
mustn't he unscrew?
mustn't we unscrew?
mustn't you unscrew?
mustn't they unscrew? 	mustn't I be unscrewing?
mustn't you be unscrewing?
mustn't he be unscrewing?
mustn't we be unscrewing?
mustn't you be unscrewing?
mustn't they be unscrewing? 	mustn't I have unscrewed?
mustn't you have unscrewed?
mustn't he have unscrewed?
mustn't we have unscrewed?
mustn't you have unscrewed?
mustn't they have unscrewed? 	mustn't I have been unscrewing?
mustn't you have been unscrewing?
mustn't he have been unscrewing?
mustn't we have been unscrewing?
mustn't you have been unscrewing?
mustn't they have been unscrewing?