must lighten
Verbo regular: lighten - lightened- lightened

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I must lighten
you must lighten
he must lighten
we must lighten
you must lighten
they must lighten 	I must be lightening
you must be lightening
he must be lightening
we must be lightening
you must be lightening
they must be lightening	I must have lightened
you must have lightened
he must have lightened
we must have lightened
you must have lightened
they must have lightened	I must have been lightening
you must have been lightening
he must have been lightening
we must have been lightening
you must have been lightening
they must have been lightening	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I mustn't lighten
you mustn't lighten
he mustn't lighten
we mustn't lighten
you mustn't lighten
they mustn't lighten 	I mustn't be lightening
you mustn't be lightening
he mustn't be lightening
we mustn't be lightening
you mustn't be lightening
they mustn't be lightening	I mustn't have lightened
you mustn't have lightened
he mustn't have lightened
we mustn't have lightened
you mustn't have lightened
they mustn't have lightened	I mustn't have been lightening
you mustn't have been lightening
he mustn't have been lightening
we mustn't have been lightening
you mustn't have been lightening
they mustn't have been lightening	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
must I lighten?
must you lighten?
must he lighten?
must we lighten?
must you lighten?
must they lighten? 	must I be lightening?
must you be lightening?
must he be lightening?
must we be lightening?
must you be lightening?
must they be lightening? 	must I have lightened?
must you have lightened?
must he have lightened?
must we have lightened?
must you have lightened?
must they have lightened? 	must I have been lightening?
must you have been lightening?
must he have been lightening?
must we have been lightening?
must you have been lightening?
must they have been lightening? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
mustn't I lighten?
mustn't you lighten?
mustn't he lighten?
mustn't we lighten?
mustn't you lighten?
mustn't they lighten? 	mustn't I be lightening?
mustn't you be lightening?
mustn't he be lightening?
mustn't we be lightening?
mustn't you be lightening?
mustn't they be lightening? 	mustn't I have lightened?
mustn't you have lightened?
mustn't he have lightened?
mustn't we have lightened?
mustn't you have lightened?
mustn't they have lightened? 	mustn't I have been lightening?
mustn't you have been lightening?
mustn't he have been lightening?
mustn't we have been lightening?
mustn't you have been lightening?
mustn't they have been lightening?