must crumple
Regular verb: crumple - crumpled- crumpled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must crumple
you must crumple
he must crumple
we must crumple
you must crumple
they must crumple 	I must be crumpling
you must be crumpling
he must be crumpling
we must be crumpling
you must be crumpling
they must be crumpling	I must have crumpled
you must have crumpled
he must have crumpled
we must have crumpled
you must have crumpled
they must have crumpled	I must have been crumpling
you must have been crumpling
he must have been crumpling
we must have been crumpling
you must have been crumpling
they must have been crumpling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not crumple
you must not crumple
he must not crumple
we must not crumple
you must not crumple
they must not crumple 	I must not be crumpling
you must not be crumpling
he must not be crumpling
we must not be crumpling
you must not be crumpling
they must not be crumpling	I must not have crumpled
you must not have crumpled
he must not have crumpled
we must not have crumpled
you must not have crumpled
they must not have crumpled	I must not have been crumpling
you must not have been crumpling
he must not have been crumpling
we must not have been crumpling
you must not have been crumpling
they must not have been crumpling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I crumple?
must you crumple?
must he crumple?
must we crumple?
must you crumple?
must they crumple? 	must I be crumpling?
must you be crumpling?
must he be crumpling?
must we be crumpling?
must you be crumpling?
must they be crumpling? 	must I have crumpled?
must you have crumpled?
must he have crumpled?
must we have crumpled?
must you have crumpled?
must they have crumpled? 	must I have been crumpling?
must you have been crumpling?
must he have been crumpling?
must we have been crumpling?
must you have been crumpling?
must they have been crumpling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not crumple?
must you not crumple?
must he not crumple?
must we not crumple?
must you not crumple?
must they not crumple? 	must I not be crumpling?
must you not be crumpling?
must he not be crumpling?
must we not be crumpling?
must you not be crumpling?
must they not be crumpling? 	must I not have crumpled?
must you not have crumpled?
must he not have crumpled?
must we not have crumpled?
must you not have crumpled?
must they not have crumpled? 	must I not have been crumpling?
must you not have been crumpling?
must he not have been crumpling?
must we not have been crumpling?
must you not have been crumpling?
must they not have been crumpling?