must lessen
Verbo regular: lessen - lessened- lessened

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must lessen
you must lessen
he must lessen
we must lessen
you must lessen
they must lessen 	I must be lessening
you must be lessening
he must be lessening
we must be lessening
you must be lessening
they must be lessening	I must have lessened
you must have lessened
he must have lessened
we must have lessened
you must have lessened
they must have lessened	I must have been lessening
you must have been lessening
he must have been lessening
we must have been lessening
you must have been lessening
they must have been lessening	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I mustn't lessen
you mustn't lessen
he mustn't lessen
we mustn't lessen
you mustn't lessen
they mustn't lessen 	I mustn't be lessening
you mustn't be lessening
he mustn't be lessening
we mustn't be lessening
you mustn't be lessening
they mustn't be lessening	I mustn't have lessened
you mustn't have lessened
he mustn't have lessened
we mustn't have lessened
you mustn't have lessened
they mustn't have lessened	I mustn't have been lessening
you mustn't have been lessening
he mustn't have been lessening
we mustn't have been lessening
you mustn't have been lessening
they mustn't have been lessening	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I lessen?
must you lessen?
must he lessen?
must we lessen?
must you lessen?
must they lessen? 	must I be lessening?
must you be lessening?
must he be lessening?
must we be lessening?
must you be lessening?
must they be lessening? 	must I have lessened?
must you have lessened?
must he have lessened?
must we have lessened?
must you have lessened?
must they have lessened? 	must I have been lessening?
must you have been lessening?
must he have been lessening?
must we have been lessening?
must you have been lessening?
must they have been lessening? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
mustn't I lessen?
mustn't you lessen?
mustn't he lessen?
mustn't we lessen?
mustn't you lessen?
mustn't they lessen? 	mustn't I be lessening?
mustn't you be lessening?
mustn't he be lessening?
mustn't we be lessening?
mustn't you be lessening?
mustn't they be lessening? 	mustn't I have lessened?
mustn't you have lessened?
mustn't he have lessened?
mustn't we have lessened?
mustn't you have lessened?
mustn't they have lessened? 	mustn't I have been lessening?
mustn't you have been lessening?
mustn't he have been lessening?
mustn't we have been lessening?
mustn't you have been lessening?
mustn't they have been lessening?