must regain
Regular verb: regain - regained- regained

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must regain
you must regain
she must regain
we must regain
you must regain
they must regain 	I must be regaining
you must be regaining
she must be regaining
we must be regaining
you must be regaining
they must be regaining	I must have regained
you must have regained
she must have regained
we must have regained
you must have regained
they must have regained	I must have been regaining
you must have been regaining
she must have been regaining
we must have been regaining
you must have been regaining
they must have been regaining	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't regain
you mustn't regain
she mustn't regain
we mustn't regain
you mustn't regain
they mustn't regain 	I mustn't be regaining
you mustn't be regaining
she mustn't be regaining
we mustn't be regaining
you mustn't be regaining
they mustn't be regaining	I mustn't have regained
you mustn't have regained
she mustn't have regained
we mustn't have regained
you mustn't have regained
they mustn't have regained	I mustn't have been regaining
you mustn't have been regaining
she mustn't have been regaining
we mustn't have been regaining
you mustn't have been regaining
they mustn't have been regaining	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I regain?
must you regain?
must she regain?
must we regain?
must you regain?
must they regain? 	must I be regaining?
must you be regaining?
must she be regaining?
must we be regaining?
must you be regaining?
must they be regaining? 	must I have regained?
must you have regained?
must she have regained?
must we have regained?
must you have regained?
must they have regained? 	must I have been regaining?
must you have been regaining?
must she have been regaining?
must we have been regaining?
must you have been regaining?
must they have been regaining? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I regain?
mustn't you regain?
mustn't she regain?
mustn't we regain?
mustn't you regain?
mustn't they regain? 	mustn't I be regaining?
mustn't you be regaining?
mustn't she be regaining?
mustn't we be regaining?
mustn't you be regaining?
mustn't they be regaining? 	mustn't I have regained?
mustn't you have regained?
mustn't she have regained?
mustn't we have regained?
mustn't you have regained?
mustn't they have regained? 	mustn't I have been regaining?
mustn't you have been regaining?
mustn't she have been regaining?
mustn't we have been regaining?
mustn't you have been regaining?
mustn't they have been regaining?