English verb conjugation
MUST RIFF

Regular verb: riff - riffed - riffed

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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

Negation

Simple form	V-ing form
I must not riff you must not riff she 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 she must not be riffing we must not be riffing you must not be riffing they must not be riffing
Perfect	V-ing perfect
I must not have riffed you must not have riffed she 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 she must not have been riffing we must not have been riffing you must not have been riffing they must not have been riffing

Interrogative form

Simple form	V-ing form
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?
Perfect	V-ing perfect
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?

Interro-negative form

Simple form	V-ing form
must I not riff? must you not riff? must she 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 she not be riffing? must we not be riffing? must you not be riffing? must they not be riffing?
Perfect	V-ing perfect
must I not have riffed? must you not have riffed? must she 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 she not have been riffing? must we not have been riffing? must you not have been riffing? must they not have been riffing?