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 cannot lengthen
you cannot lengthen
he cannot lengthen
we cannot lengthen
you cannot lengthen
they cannot lengthen 	I cannot be lengthening
you cannot be lengthening
he cannot be lengthening
we cannot be lengthening
you cannot be lengthening
they cannot be lengthening	I cannot have lengthened
you cannot have lengthened
he cannot have lengthened
we cannot have lengthened
you cannot have lengthened
they cannot have lengthened	I cannot have been lengthening
you cannot have been lengthening
he cannot have been lengthening
we cannot have been lengthening
you cannot have been lengthening
they cannot 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 I not lengthen?
can you not lengthen?
can he not lengthen?
can we not lengthen?
can you not lengthen?
can they not lengthen? 	can I not be lengthening?
can you not be lengthening?
can he not be lengthening?
can we not be lengthening?
can you not be lengthening?
can they not be lengthening? 	can I not have lengthened?
can you not have lengthened?
can he not have lengthened?
can we not have lengthened?
can you not have lengthened?
can they not have lengthened? 	can I not have been lengthening?
can you not have been lengthening?
can he not have been lengthening?
can we not have been lengthening?
can you not have been lengthening?
can they not have been lengthening?