must stumble
Regular verb: stumble - stumbled- stumbled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must stumble
you must stumble
she must stumble
we must stumble
you must stumble
they must stumble 	I must be stumbling
you must be stumbling
she must be stumbling
we must be stumbling
you must be stumbling
they must be stumbling	I must have stumbled
you must have stumbled
she must have stumbled
we must have stumbled
you must have stumbled
they must have stumbled	I must have been stumbling
you must have been stumbling
she must have been stumbling
we must have been stumbling
you must have been stumbling
they must have been stumbling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't stumble
you mustn't stumble
she mustn't stumble
we mustn't stumble
you mustn't stumble
they mustn't stumble 	I mustn't be stumbling
you mustn't be stumbling
she mustn't be stumbling
we mustn't be stumbling
you mustn't be stumbling
they mustn't be stumbling	I mustn't have stumbled
you mustn't have stumbled
she mustn't have stumbled
we mustn't have stumbled
you mustn't have stumbled
they mustn't have stumbled	I mustn't have been stumbling
you mustn't have been stumbling
she mustn't have been stumbling
we mustn't have been stumbling
you mustn't have been stumbling
they mustn't have been stumbling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I stumble?
must you stumble?
must she stumble?
must we stumble?
must you stumble?
must they stumble? 	must I be stumbling?
must you be stumbling?
must she be stumbling?
must we be stumbling?
must you be stumbling?
must they be stumbling? 	must I have stumbled?
must you have stumbled?
must she have stumbled?
must we have stumbled?
must you have stumbled?
must they have stumbled? 	must I have been stumbling?
must you have been stumbling?
must she have been stumbling?
must we have been stumbling?
must you have been stumbling?
must they have been stumbling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I stumble?
mustn't you stumble?
mustn't she stumble?
mustn't we stumble?
mustn't you stumble?
mustn't they stumble? 	mustn't I be stumbling?
mustn't you be stumbling?
mustn't she be stumbling?
mustn't we be stumbling?
mustn't you be stumbling?
mustn't they be stumbling? 	mustn't I have stumbled?
mustn't you have stumbled?
mustn't she have stumbled?
mustn't we have stumbled?
mustn't you have stumbled?
mustn't they have stumbled? 	mustn't I have been stumbling?
mustn't you have been stumbling?
mustn't she have been stumbling?
mustn't we have been stumbling?
mustn't you have been stumbling?
mustn't they have been stumbling?