must prolong
Regular verb: prolong - prolonged- prolonged

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must prolong
you must prolong
he must prolong
we must prolong
you must prolong
they must prolong 	I must be prolonging
you must be prolonging
he must be prolonging
we must be prolonging
you must be prolonging
they must be prolonging	I must have prolonged
you must have prolonged
he must have prolonged
we must have prolonged
you must have prolonged
they must have prolonged	I must have been prolonging
you must have been prolonging
he must have been prolonging
we must have been prolonging
you must have been prolonging
they must have been prolonging	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't prolong
you mustn't prolong
he mustn't prolong
we mustn't prolong
you mustn't prolong
they mustn't prolong 	I mustn't be prolonging
you mustn't be prolonging
he mustn't be prolonging
we mustn't be prolonging
you mustn't be prolonging
they mustn't be prolonging	I mustn't have prolonged
you mustn't have prolonged
he mustn't have prolonged
we mustn't have prolonged
you mustn't have prolonged
they mustn't have prolonged	I mustn't have been prolonging
you mustn't have been prolonging
he mustn't have been prolonging
we mustn't have been prolonging
you mustn't have been prolonging
they mustn't have been prolonging	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I prolong?
must you prolong?
must he prolong?
must we prolong?
must you prolong?
must they prolong? 	must I be prolonging?
must you be prolonging?
must he be prolonging?
must we be prolonging?
must you be prolonging?
must they be prolonging? 	must I have prolonged?
must you have prolonged?
must he have prolonged?
must we have prolonged?
must you have prolonged?
must they have prolonged? 	must I have been prolonging?
must you have been prolonging?
must he have been prolonging?
must we have been prolonging?
must you have been prolonging?
must they have been prolonging? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I prolong?
mustn't you prolong?
mustn't he prolong?
mustn't we prolong?
mustn't you prolong?
mustn't they prolong? 	mustn't I be prolonging?
mustn't you be prolonging?
mustn't he be prolonging?
mustn't we be prolonging?
mustn't you be prolonging?
mustn't they be prolonging? 	mustn't I have prolonged?
mustn't you have prolonged?
mustn't he have prolonged?
mustn't we have prolonged?
mustn't you have prolonged?
mustn't they have prolonged? 	mustn't I have been prolonging?
mustn't you have been prolonging?
mustn't he have been prolonging?
mustn't we have been prolonging?
mustn't you have been prolonging?
mustn't they have been prolonging?