must lumber
Regular verb: lumber - lumbered- lumbered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must lumber
you must lumber
she must lumber
we must lumber
you must lumber
they must lumber 	I must be lumbering
you must be lumbering
she must be lumbering
we must be lumbering
you must be lumbering
they must be lumbering	I must have lumbered
you must have lumbered
she 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
she must have been lumbering
we must have been lumbering
you must have been lumbering
they must have been lumbering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't lumber
you mustn't lumber
she mustn't lumber
we mustn't lumber
you mustn't lumber
they mustn't lumber 	I mustn't be lumbering
you mustn't be lumbering
she mustn't be lumbering
we mustn't be lumbering
you mustn't be lumbering
they mustn't be lumbering	I mustn't have lumbered
you mustn't have lumbered
she mustn't have lumbered
we mustn't have lumbered
you mustn't have lumbered
they mustn't have lumbered	I mustn't have been lumbering
you mustn't have been lumbering
she mustn't have been lumbering
we mustn't have been lumbering
you mustn't have been lumbering
they mustn't have been lumbering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I lumber?
must you lumber?
must she lumber?
must we lumber?
must you lumber?
must they lumber? 	must I be lumbering?
must you be lumbering?
must she be lumbering?
must we be lumbering?
must you be lumbering?
must they be lumbering? 	must I have lumbered?
must you have lumbered?
must she 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 she have been lumbering?
must we have been lumbering?
must you have been lumbering?
must they have been lumbering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I lumber?
mustn't you lumber?
mustn't she lumber?
mustn't we lumber?
mustn't you lumber?
mustn't they lumber? 	mustn't I be lumbering?
mustn't you be lumbering?
mustn't she be lumbering?
mustn't we be lumbering?
mustn't you be lumbering?
mustn't they be lumbering? 	mustn't I have lumbered?
mustn't you have lumbered?
mustn't she have lumbered?
mustn't we have lumbered?
mustn't you have lumbered?
mustn't they have lumbered? 	mustn't I have been lumbering?
mustn't you have been lumbering?
mustn't she have been lumbering?
mustn't we have been lumbering?
mustn't you have been lumbering?
mustn't they have been lumbering?