must stumble
Regular verb: stumble - stumbled- stumbled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must stumble
you must stumble
he must stumble
we must stumble
you must stumble
they must stumble 	I must be stumbling
you must be stumbling
he must be stumbling
we must be stumbling
you must be stumbling
they must be stumbling	I must have stumbled
you must have stumbled
he 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
he 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 must not stumble
you must not stumble
he must not stumble
we must not stumble
you must not stumble
they must not stumble 	I must not be stumbling
you must not be stumbling
he must not be stumbling
we must not be stumbling
you must not be stumbling
they must not be stumbling	I must not have stumbled
you must not have stumbled
he must not have stumbled
we must not have stumbled
you must not have stumbled
they must not have stumbled	I must not have been stumbling
you must not have been stumbling
he must not have been stumbling
we must not have been stumbling
you must not have been stumbling
they must not have been stumbling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I stumble?
must you stumble?
must he stumble?
must we stumble?
must you stumble?
must they stumble? 	must I be stumbling?
must you be stumbling?
must he be stumbling?
must we be stumbling?
must you be stumbling?
must they be stumbling? 	must I have stumbled?
must you have stumbled?
must he 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 he 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 	
must I not stumble?
must you not stumble?
must he not stumble?
must we not stumble?
must you not stumble?
must they not stumble? 	must I not be stumbling?
must you not be stumbling?
must he not be stumbling?
must we not be stumbling?
must you not be stumbling?
must they not be stumbling? 	must I not have stumbled?
must you not have stumbled?
must he not have stumbled?
must we not have stumbled?
must you not have stumbled?
must they not have stumbled? 	must I not have been stumbling?
must you not have been stumbling?
must he not have been stumbling?
must we not have been stumbling?
must you not have been stumbling?
must they not have been stumbling?