must vary
Regular verb: vary - varied- varied

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must vary
you must vary
he must vary
we must vary
you must vary
they must vary 	I must be varying
you must be varying
he must be varying
we must be varying
you must be varying
they must be varying	I must have varied
you must have varied
he must have varied
we must have varied
you must have varied
they must have varied	I must have been varying
you must have been varying
he must have been varying
we must have been varying
you must have been varying
they must have been varying	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't vary
you mustn't vary
he mustn't vary
we mustn't vary
you mustn't vary
they mustn't vary 	I mustn't be varying
you mustn't be varying
he mustn't be varying
we mustn't be varying
you mustn't be varying
they mustn't be varying	I mustn't have varied
you mustn't have varied
he mustn't have varied
we mustn't have varied
you mustn't have varied
they mustn't have varied	I mustn't have been varying
you mustn't have been varying
he mustn't have been varying
we mustn't have been varying
you mustn't have been varying
they mustn't have been varying	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I vary?
must you vary?
must he vary?
must we vary?
must you vary?
must they vary? 	must I be varying?
must you be varying?
must he be varying?
must we be varying?
must you be varying?
must they be varying? 	must I have varied?
must you have varied?
must he have varied?
must we have varied?
must you have varied?
must they have varied? 	must I have been varying?
must you have been varying?
must he have been varying?
must we have been varying?
must you have been varying?
must they have been varying? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I vary?
mustn't you vary?
mustn't he vary?
mustn't we vary?
mustn't you vary?
mustn't they vary? 	mustn't I be varying?
mustn't you be varying?
mustn't he be varying?
mustn't we be varying?
mustn't you be varying?
mustn't they be varying? 	mustn't I have varied?
mustn't you have varied?
mustn't he have varied?
mustn't we have varied?
mustn't you have varied?
mustn't they have varied? 	mustn't I have been varying?
mustn't you have been varying?
mustn't he have been varying?
mustn't we have been varying?
mustn't you have been varying?
mustn't they have been varying?