must butter
Regular verb: butter - buttered- buttered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must butter
you must butter
she must butter
we must butter
you must butter
they must butter 	I must be buttering
you must be buttering
she must be buttering
we must be buttering
you must be buttering
they must be buttering	I must have buttered
you must have buttered
she 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
she 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
she 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
she 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
she 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
she 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 she butter?
must we butter?
must you butter?
must they butter? 	must I be buttering?
must you be buttering?
must she be buttering?
must we be buttering?
must you be buttering?
must they be buttering? 	must I have buttered?
must you have buttered?
must she 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 she 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 she 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 she 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 she 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 she have been buttering?
mustn't we have been buttering?
mustn't you have been buttering?
mustn't they have been buttering?