must tighten
Verbo regular: tighten - tightened- tightened

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I must tighten
you must tighten
he must tighten
we must tighten
you must tighten
they must tighten 	I must be tightening
you must be tightening
he must be tightening
we must be tightening
you must be tightening
they must be tightening	I must have tightened
you must have tightened
he 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
he must have been tightening
we must have been tightening
you must have been tightening
they must have been tightening	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I mustn't tighten
you mustn't tighten
he 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
he 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
he 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
he mustn't have been tightening
we mustn't have been tightening
you mustn't have been tightening
they mustn't have been tightening	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
must I tighten?
must you tighten?
must he tighten?
must we tighten?
must you tighten?
must they tighten? 	must I be tightening?
must you be tightening?
must he be tightening?
must we be tightening?
must you be tightening?
must they be tightening? 	must I have tightened?
must you have tightened?
must he 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 he have been tightening?
must we have been tightening?
must you have been tightening?
must they have been tightening? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
mustn't I tighten?
mustn't you tighten?
mustn't he 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 he 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 he 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 he have been tightening?
mustn't we have been tightening?
mustn't you have been tightening?
mustn't they have been tightening?