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 must not butter
you must not butter
she must not butter
we must not butter
you must not butter
they must not butter 	I must not be buttering
you must not be buttering
she must not be buttering
we must not be buttering
you must not be buttering
they must not be buttering	I must not have buttered
you must not have buttered
she must not have buttered
we must not have buttered
you must not have buttered
they must not have buttered	I must not have been buttering
you must not have been buttering
she must not have been buttering
we must not have been buttering
you must not have been buttering
they must not 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 	
must I not butter?
must you not butter?
must she not butter?
must we not butter?
must you not butter?
must they not butter? 	must I not be buttering?
must you not be buttering?
must she not be buttering?
must we not be buttering?
must you not be buttering?
must they not be buttering? 	must I not have buttered?
must you not have buttered?
must she not have buttered?
must we not have buttered?
must you not have buttered?
must they not have buttered? 	must I not have been buttering?
must you not have been buttering?
must she not have been buttering?
must we not have been buttering?
must you not have been buttering?
must they not have been buttering?