must lumber
Verbo regular: lumber - lumbered- lumbered

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must lumber
you must lumber
he must lumber
we must lumber
you must lumber
they must lumber 	I must be lumbering
you must be lumbering
he must be lumbering
we must be lumbering
you must be lumbering
they must be lumbering	I must have lumbered
you must have lumbered
he must have lumbered
we must have lumbered
you must have lumbered
they must have lumbered	I must have been lumbering
you must have been lumbering
he must have been lumbering
we must have been lumbering
you must have been lumbering
they must have been lumbering	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must not lumber
you must not lumber
he must not lumber
we must not lumber
you must not lumber
they must not lumber 	I must not be lumbering
you must not be lumbering
he must not be lumbering
we must not be lumbering
you must not be lumbering
they must not be lumbering	I must not have lumbered
you must not have lumbered
he must not have lumbered
we must not have lumbered
you must not have lumbered
they must not have lumbered	I must not have been lumbering
you must not have been lumbering
he must not have been lumbering
we must not have been lumbering
you must not have been lumbering
they must not have been lumbering	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I lumber?
must you lumber?
must he lumber?
must we lumber?
must you lumber?
must they lumber? 	must I be lumbering?
must you be lumbering?
must he be lumbering?
must we be lumbering?
must you be lumbering?
must they be lumbering? 	must I have lumbered?
must you have lumbered?
must he have lumbered?
must we have lumbered?
must you have lumbered?
must they have lumbered? 	must I have been lumbering?
must you have been lumbering?
must he have been lumbering?
must we have been lumbering?
must you have been lumbering?
must they have been lumbering? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I not lumber?
must you not lumber?
must he not lumber?
must we not lumber?
must you not lumber?
must they not lumber? 	must I not be lumbering?
must you not be lumbering?
must he not be lumbering?
must we not be lumbering?
must you not be lumbering?
must they not be lumbering? 	must I not have lumbered?
must you not have lumbered?
must he not have lumbered?
must we not have lumbered?
must you not have lumbered?
must they not have lumbered? 	must I not have been lumbering?
must you not have been lumbering?
must he not have been lumbering?
must we not have been lumbering?
must you not have been lumbering?
must they not have been lumbering?