must butter
Regular verb: butter - buttered- buttered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must butter
you must butter
he must butter
we must butter
you must butter
they must butter 	I must be buttering
you must be buttering
he must be buttering
we must be buttering
you must be buttering
they must be buttering	I must have buttered
you must have buttered
he must have buttered
we must have buttered
you must have buttered
they must have buttered	I must have been buttering
you must have been buttering
he must have been buttering
we must have been buttering
you must have been buttering
they must have been buttering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't butter
you mustn't butter
he mustn't butter
we mustn't butter
you mustn't butter
they mustn't butter 	I mustn't be buttering
you mustn't be buttering
he mustn't be buttering
we mustn't be buttering
you mustn't be buttering
they mustn't be buttering	I mustn't have buttered
you mustn't have buttered
he mustn't have buttered
we mustn't have buttered
you mustn't have buttered
they mustn't have buttered	I mustn't have been buttering
you mustn't have been buttering
he mustn't have been buttering
we mustn't have been buttering
you mustn't have been buttering
they mustn't have been buttering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I butter?
must you butter?
must he butter?
must we butter?
must you butter?
must they butter? 	must I be buttering?
must you be buttering?
must he be buttering?
must we be buttering?
must you be buttering?
must they be buttering? 	must I have buttered?
must you have buttered?
must he have buttered?
must we have buttered?
must you have buttered?
must they have buttered? 	must I have been buttering?
must you have been buttering?
must he have been buttering?
must we have been buttering?
must you have been buttering?
must they have been buttering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I butter?
mustn't you butter?
mustn't he butter?
mustn't we butter?
mustn't you butter?
mustn't they butter? 	mustn't I be buttering?
mustn't you be buttering?
mustn't he be buttering?
mustn't we be buttering?
mustn't you be buttering?
mustn't they be buttering? 	mustn't I have buttered?
mustn't you have buttered?
mustn't he have buttered?
mustn't we have buttered?
mustn't you have buttered?
mustn't they have buttered? 	mustn't I have been buttering?
mustn't you have been buttering?
mustn't he have been buttering?
mustn't we have been buttering?
mustn't you have been buttering?
mustn't they have been buttering?