English verb conjugation
MUST BUTTER

Regular verb: butter - buttered - buttered

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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
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
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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?