must spiff
Regular verb: spiff - spiffed- spiffed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must spiff
you must spiff
he must spiff
we must spiff
you must spiff
they must spiff 	I must be spiffing
you must be spiffing
he must be spiffing
we must be spiffing
you must be spiffing
they must be spiffing	I must have spiffed
you must have spiffed
he must have spiffed
we must have spiffed
you must have spiffed
they must have spiffed	I must have been spiffing
you must have been spiffing
he must have been spiffing
we must have been spiffing
you must have been spiffing
they must have been spiffing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't spiff
you mustn't spiff
he mustn't spiff
we mustn't spiff
you mustn't spiff
they mustn't spiff 	I mustn't be spiffing
you mustn't be spiffing
he mustn't be spiffing
we mustn't be spiffing
you mustn't be spiffing
they mustn't be spiffing	I mustn't have spiffed
you mustn't have spiffed
he mustn't have spiffed
we mustn't have spiffed
you mustn't have spiffed
they mustn't have spiffed	I mustn't have been spiffing
you mustn't have been spiffing
he mustn't have been spiffing
we mustn't have been spiffing
you mustn't have been spiffing
they mustn't have been spiffing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I spiff?
must you spiff?
must he spiff?
must we spiff?
must you spiff?
must they spiff? 	must I be spiffing?
must you be spiffing?
must he be spiffing?
must we be spiffing?
must you be spiffing?
must they be spiffing? 	must I have spiffed?
must you have spiffed?
must he have spiffed?
must we have spiffed?
must you have spiffed?
must they have spiffed? 	must I have been spiffing?
must you have been spiffing?
must he have been spiffing?
must we have been spiffing?
must you have been spiffing?
must they have been spiffing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I spiff?
mustn't you spiff?
mustn't he spiff?
mustn't we spiff?
mustn't you spiff?
mustn't they spiff? 	mustn't I be spiffing?
mustn't you be spiffing?
mustn't he be spiffing?
mustn't we be spiffing?
mustn't you be spiffing?
mustn't they be spiffing? 	mustn't I have spiffed?
mustn't you have spiffed?
mustn't he have spiffed?
mustn't we have spiffed?
mustn't you have spiffed?
mustn't they have spiffed? 	mustn't I have been spiffing?
mustn't you have been spiffing?
mustn't he have been spiffing?
mustn't we have been spiffing?
mustn't you have been spiffing?
mustn't they have been spiffing?