must tighten
Regular verb: tighten - tightened- tightened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must tighten
you must tighten
she must tighten
we must tighten
you must tighten
they must tighten 	I must be tightening
you must be tightening
she must be tightening
we must be tightening
you must be tightening
they must be tightening	I must have tightened
you must have tightened
she must have tightened
we must have tightened
you must have tightened
they must have tightened	I must have been tightening
you must have been tightening
she must have been tightening
we must have been tightening
you must have been tightening
they must have been tightening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't tighten
you mustn't tighten
she mustn't tighten
we mustn't tighten
you mustn't tighten
they mustn't tighten 	I mustn't be tightening
you mustn't be tightening
she mustn't be tightening
we mustn't be tightening
you mustn't be tightening
they mustn't be tightening	I mustn't have tightened
you mustn't have tightened
she mustn't have tightened
we mustn't have tightened
you mustn't have tightened
they mustn't have tightened	I mustn't have been tightening
you mustn't have been tightening
she mustn't have been tightening
we mustn't have been tightening
you mustn't have been tightening
they mustn't have been tightening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I tighten?
must you tighten?
must she tighten?
must we tighten?
must you tighten?
must they tighten? 	must I be tightening?
must you be tightening?
must she be tightening?
must we be tightening?
must you be tightening?
must they be tightening? 	must I have tightened?
must you have tightened?
must she have tightened?
must we have tightened?
must you have tightened?
must they have tightened? 	must I have been tightening?
must you have been tightening?
must she have been tightening?
must we have been tightening?
must you have been tightening?
must they have been tightening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I tighten?
mustn't you tighten?
mustn't she tighten?
mustn't we tighten?
mustn't you tighten?
mustn't they tighten? 	mustn't I be tightening?
mustn't you be tightening?
mustn't she be tightening?
mustn't we be tightening?
mustn't you be tightening?
mustn't they be tightening? 	mustn't I have tightened?
mustn't you have tightened?
mustn't she have tightened?
mustn't we have tightened?
mustn't you have tightened?
mustn't they have tightened? 	mustn't I have been tightening?
mustn't you have been tightening?
mustn't she have been tightening?
mustn't we have been tightening?
mustn't you have been tightening?
mustn't they have been tightening?