must riff
Verbe régulier : riff - riffed- riffed

Affirmation 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
I must riff
you must riff
she must riff
we must riff
you must riff
they must riff 	I must be riffing
you must be riffing
she must be riffing
we must be riffing
you must be riffing
they must be riffing	I must have riffed
you must have riffed
she must have riffed
we must have riffed
you must have riffed
they must have riffed	I must have been riffing
you must have been riffing
she must have been riffing
we must have been riffing
you must have been riffing
they must have been riffing	

Négation 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
I mustn't riff
you mustn't riff
she mustn't riff
we mustn't riff
you mustn't riff
they mustn't riff 	I mustn't be riffing
you mustn't be riffing
she mustn't be riffing
we mustn't be riffing
you mustn't be riffing
they mustn't be riffing	I mustn't have riffed
you mustn't have riffed
she mustn't have riffed
we mustn't have riffed
you mustn't have riffed
they mustn't have riffed	I mustn't have been riffing
you mustn't have been riffing
she mustn't have been riffing
we mustn't have been riffing
you mustn't have been riffing
they mustn't have been riffing	

Forme interrogative 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
must I riff?
must you riff?
must she riff?
must we riff?
must you riff?
must they riff? 	must I be riffing?
must you be riffing?
must she be riffing?
must we be riffing?
must you be riffing?
must they be riffing? 	must I have riffed?
must you have riffed?
must she have riffed?
must we have riffed?
must you have riffed?
must they have riffed? 	must I have been riffing?
must you have been riffing?
must she have been riffing?
must we have been riffing?
must you have been riffing?
must they have been riffing? 	

Forme interro-négative 	
Forme simple 	Forme en V-ing 	Perfect 	Perfect en V-ing 	
mustn't I riff?
mustn't you riff?
mustn't she riff?
mustn't we riff?
mustn't you riff?
mustn't they riff? 	mustn't I be riffing?
mustn't you be riffing?
mustn't she be riffing?
mustn't we be riffing?
mustn't you be riffing?
mustn't they be riffing? 	mustn't I have riffed?
mustn't you have riffed?
mustn't she have riffed?
mustn't we have riffed?
mustn't you have riffed?
mustn't they have riffed? 	mustn't I have been riffing?
mustn't you have been riffing?
mustn't she have been riffing?
mustn't we have been riffing?
mustn't you have been riffing?
mustn't they have been riffing?