must riff
Verbo regular: riff - riffed- riffed

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must riff
you must riff
he must riff
we must riff
you must riff
they must riff 	I must be riffing
you must be riffing
he must be riffing
we must be riffing
you must be riffing
they must be riffing	I must have riffed
you must have riffed
he 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
he must have been riffing
we must have been riffing
you must have been riffing
they must have been riffing	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must not riff
you must not riff
he must not riff
we must not riff
you must not riff
they must not riff 	I must not be riffing
you must not be riffing
he must not be riffing
we must not be riffing
you must not be riffing
they must not be riffing	I must not have riffed
you must not have riffed
he must not have riffed
we must not have riffed
you must not have riffed
they must not have riffed	I must not have been riffing
you must not have been riffing
he must not have been riffing
we must not have been riffing
you must not have been riffing
they must not have been riffing	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I riff?
must you riff?
must he riff?
must we riff?
must you riff?
must they riff? 	must I be riffing?
must you be riffing?
must he be riffing?
must we be riffing?
must you be riffing?
must they be riffing? 	must I have riffed?
must you have riffed?
must he 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 he have been riffing?
must we have been riffing?
must you have been riffing?
must they have been riffing? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I not riff?
must you not riff?
must he not riff?
must we not riff?
must you not riff?
must they not riff? 	must I not be riffing?
must you not be riffing?
must he not be riffing?
must we not be riffing?
must you not be riffing?
must they not be riffing? 	must I not have riffed?
must you not have riffed?
must he not have riffed?
must we not have riffed?
must you not have riffed?
must they not have riffed? 	must I not have been riffing?
must you not have been riffing?
must he not have been riffing?
must we not have been riffing?
must you not have been riffing?
must they not have been riffing?