must rumble
Regular verb: rumble - rumbled- rumbled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must rumble
you must rumble
he must rumble
we must rumble
you must rumble
they must rumble 	I must be rumbling
you must be rumbling
he must be rumbling
we must be rumbling
you must be rumbling
they must be rumbling	I must have rumbled
you must have rumbled
he must have rumbled
we must have rumbled
you must have rumbled
they must have rumbled	I must have been rumbling
you must have been rumbling
he must have been rumbling
we must have been rumbling
you must have been rumbling
they must have been rumbling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not rumble
you must not rumble
he must not rumble
we must not rumble
you must not rumble
they must not rumble 	I must not be rumbling
you must not be rumbling
he must not be rumbling
we must not be rumbling
you must not be rumbling
they must not be rumbling	I must not have rumbled
you must not have rumbled
he must not have rumbled
we must not have rumbled
you must not have rumbled
they must not have rumbled	I must not have been rumbling
you must not have been rumbling
he must not have been rumbling
we must not have been rumbling
you must not have been rumbling
they must not have been rumbling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I rumble?
must you rumble?
must he rumble?
must we rumble?
must you rumble?
must they rumble? 	must I be rumbling?
must you be rumbling?
must he be rumbling?
must we be rumbling?
must you be rumbling?
must they be rumbling? 	must I have rumbled?
must you have rumbled?
must he have rumbled?
must we have rumbled?
must you have rumbled?
must they have rumbled? 	must I have been rumbling?
must you have been rumbling?
must he have been rumbling?
must we have been rumbling?
must you have been rumbling?
must they have been rumbling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not rumble?
must you not rumble?
must he not rumble?
must we not rumble?
must you not rumble?
must they not rumble? 	must I not be rumbling?
must you not be rumbling?
must he not be rumbling?
must we not be rumbling?
must you not be rumbling?
must they not be rumbling? 	must I not have rumbled?
must you not have rumbled?
must he not have rumbled?
must we not have rumbled?
must you not have rumbled?
must they not have rumbled? 	must I not have been rumbling?
must you not have been rumbling?
must he not have been rumbling?
must we not have been rumbling?
must you not have been rumbling?
must they not have been rumbling?