can lengthen
Verbo regular: lengthen - lengthened- lengthened

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I can lengthen
you can lengthen
he can lengthen
we can lengthen
you can lengthen
they can lengthen 	I can be lengthening
you can be lengthening
he can be lengthening
we can be lengthening
you can be lengthening
they can be lengthening	I can have lengthened
you can have lengthened
he can have lengthened
we can have lengthened
you can have lengthened
they can have lengthened	I can have been lengthening
you can have been lengthening
he can have been lengthening
we can have been lengthening
you can have been lengthening
they can have been lengthening	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I can't lengthen
you can't lengthen
he can't lengthen
we can't lengthen
you can't lengthen
they can't lengthen 	I can't be lengthening
you can't be lengthening
he can't be lengthening
we can't be lengthening
you can't be lengthening
they can't be lengthening	I can't have lengthened
you can't have lengthened
he can't have lengthened
we can't have lengthened
you can't have lengthened
they can't have lengthened	I can't have been lengthening
you can't have been lengthening
he can't have been lengthening
we can't have been lengthening
you can't have been lengthening
they can't have been lengthening	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
can I lengthen?
can you lengthen?
can he lengthen?
can we lengthen?
can you lengthen?
can they lengthen? 	can I be lengthening?
can you be lengthening?
can he be lengthening?
can we be lengthening?
can you be lengthening?
can they be lengthening? 	can I have lengthened?
can you have lengthened?
can he have lengthened?
can we have lengthened?
can you have lengthened?
can they have lengthened? 	can I have been lengthening?
can you have been lengthening?
can he have been lengthening?
can we have been lengthening?
can you have been lengthening?
can they have been lengthening? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
can't I lengthen?
can't you lengthen?
can't he lengthen?
can't we lengthen?
can't you lengthen?
can't they lengthen? 	can't I be lengthening?
can't you be lengthening?
can't he be lengthening?
can't we be lengthening?
can't you be lengthening?
can't they be lengthening? 	can't I have lengthened?
can't you have lengthened?
can't he have lengthened?
can't we have lengthened?
can't you have lengthened?
can't they have lengthened? 	can't I have been lengthening?
can't you have been lengthening?
can't he have been lengthening?
can't we have been lengthening?
can't you have been lengthening?
can't they have been lengthening?