English verb conjugation
MUST BUY

Irregular verb: buy - bought - bought

Affirmation

Simple form	V-ing form
I must buy you must buy she must buy we must buy you must buy they must buy	I must be buying you must be buying she must be buying we must be buying you must be buying they must be buying
Perfect	V-ing perfect
I must have bought you must have bought she must have bought we must have bought you must have bought they must have bought	I must have been buying you must have been buying she must have been buying we must have been buying you must have been buying they must have been buying

Negation

Simple form	V-ing form
I mustn't buy you mustn't buy she mustn't buy we mustn't buy you mustn't buy they mustn't buy	I mustn't be buying you mustn't be buying she mustn't be buying we mustn't be buying you mustn't be buying they mustn't be buying
Perfect	V-ing perfect
I mustn't have bought you mustn't have bought she mustn't have bought we mustn't have bought you mustn't have bought they mustn't have bought	I mustn't have been buying you mustn't have been buying she mustn't have been buying we mustn't have been buying you mustn't have been buying they mustn't have been buying

Interrogative form

Simple form	V-ing form
must I buy? must you buy? must she buy? must we buy? must you buy? must they buy?	must I be buying? must you be buying? must she be buying? must we be buying? must you be buying? must they be buying?
Perfect	V-ing perfect
must I have bought? must you have bought? must she have bought? must we have bought? must you have bought? must they have bought?	must I have been buying? must you have been buying? must she have been buying? must we have been buying? must you have been buying? must they have been buying?

Interro-negative form

Simple form	V-ing form
mustn't I buy? mustn't you buy? mustn't she buy? mustn't we buy? mustn't you buy? mustn't they buy?	mustn't I be buying? mustn't you be buying? mustn't she be buying? mustn't we be buying? mustn't you be buying? mustn't they be buying?
Perfect	V-ing perfect
mustn't I have bought? mustn't you have bought? mustn't she have bought? mustn't we have bought? mustn't you have bought? mustn't they have bought?	mustn't I have been buying? mustn't you have been buying? mustn't she have been buying? mustn't we have been buying? mustn't you have been buying? mustn't they have been buying?