must lengthen
Verbo regular: lengthen - lengthened- lengthened

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I must lengthen
you must lengthen
he must lengthen
we must lengthen
you must lengthen
they must lengthen 	I must be lengthening
you must be lengthening
he must be lengthening
we must be lengthening
you must be lengthening
they must be lengthening	I must have lengthened
you must have lengthened
he must have lengthened
we must have lengthened
you must have lengthened
they must have lengthened	I must have been lengthening
you must have been lengthening
he must have been lengthening
we must have been lengthening
you must have been lengthening
they must have been lengthening	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I must not lengthen
you must not lengthen
he must not lengthen
we must not lengthen
you must not lengthen
they must not lengthen 	I must not be lengthening
you must not be lengthening
he must not be lengthening
we must not be lengthening
you must not be lengthening
they must not be lengthening	I must not have lengthened
you must not have lengthened
he must not have lengthened
we must not have lengthened
you must not have lengthened
they must not have lengthened	I must not have been lengthening
you must not have been lengthening
he must not have been lengthening
we must not have been lengthening
you must not have been lengthening
they must not have been lengthening	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
must I lengthen?
must you lengthen?
must he lengthen?
must we lengthen?
must you lengthen?
must they lengthen? 	must I be lengthening?
must you be lengthening?
must he be lengthening?
must we be lengthening?
must you be lengthening?
must they be lengthening? 	must I have lengthened?
must you have lengthened?
must he have lengthened?
must we have lengthened?
must you have lengthened?
must they have lengthened? 	must I have been lengthening?
must you have been lengthening?
must he have been lengthening?
must we have been lengthening?
must you have been lengthening?
must they have been lengthening? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
must I not lengthen?
must you not lengthen?
must he not lengthen?
must we not lengthen?
must you not lengthen?
must they not lengthen? 	must I not be lengthening?
must you not be lengthening?
must he not be lengthening?
must we not be lengthening?
must you not be lengthening?
must they not be lengthening? 	must I not have lengthened?
must you not have lengthened?
must he not have lengthened?
must we not have lengthened?
must you not have lengthened?
must they not have lengthened? 	must I not have been lengthening?
must you not have been lengthening?
must he not have been lengthening?
must we not have been lengthening?
must you not have been lengthening?
must they not have been lengthening?