must collapse
Regular verb: collapse - collapsed- collapsed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must collapse
you must collapse
he must collapse
we must collapse
you must collapse
they must collapse 	I must be collapsing
you must be collapsing
he must be collapsing
we must be collapsing
you must be collapsing
they must be collapsing	I must have collapsed
you must have collapsed
he must have collapsed
we must have collapsed
you must have collapsed
they must have collapsed	I must have been collapsing
you must have been collapsing
he must have been collapsing
we must have been collapsing
you must have been collapsing
they must have been collapsing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't collapse
you mustn't collapse
he mustn't collapse
we mustn't collapse
you mustn't collapse
they mustn't collapse 	I mustn't be collapsing
you mustn't be collapsing
he mustn't be collapsing
we mustn't be collapsing
you mustn't be collapsing
they mustn't be collapsing	I mustn't have collapsed
you mustn't have collapsed
he mustn't have collapsed
we mustn't have collapsed
you mustn't have collapsed
they mustn't have collapsed	I mustn't have been collapsing
you mustn't have been collapsing
he mustn't have been collapsing
we mustn't have been collapsing
you mustn't have been collapsing
they mustn't have been collapsing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I collapse?
must you collapse?
must he collapse?
must we collapse?
must you collapse?
must they collapse? 	must I be collapsing?
must you be collapsing?
must he be collapsing?
must we be collapsing?
must you be collapsing?
must they be collapsing? 	must I have collapsed?
must you have collapsed?
must he have collapsed?
must we have collapsed?
must you have collapsed?
must they have collapsed? 	must I have been collapsing?
must you have been collapsing?
must he have been collapsing?
must we have been collapsing?
must you have been collapsing?
must they have been collapsing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I collapse?
mustn't you collapse?
mustn't he collapse?
mustn't we collapse?
mustn't you collapse?
mustn't they collapse? 	mustn't I be collapsing?
mustn't you be collapsing?
mustn't he be collapsing?
mustn't we be collapsing?
mustn't you be collapsing?
mustn't they be collapsing? 	mustn't I have collapsed?
mustn't you have collapsed?
mustn't he have collapsed?
mustn't we have collapsed?
mustn't you have collapsed?
mustn't they have collapsed? 	mustn't I have been collapsing?
mustn't you have been collapsing?
mustn't he have been collapsing?
mustn't we have been collapsing?
mustn't you have been collapsing?
mustn't they have been collapsing?