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 must not buy you must not buy she must not buy we must not buy you must not buy they must not buy	I must not be buying you must not be buying she must not be buying we must not be buying you must not be buying they must not be buying
Perfect	V-ing perfect
I must not have bought you must not have bought she must not have bought we must not have bought you must not have bought they must not have bought	I must not have been buying you must not have been buying she must not have been buying we must not have been buying you must not have been buying they must not 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
must I not buy? must you not buy? must she not buy? must we not buy? must you not buy? must they not buy?	must I not be buying? must you not be buying? must she not be buying? must we not be buying? must you not be buying? must they not be buying?
Perfect	V-ing perfect
must I not have bought? must you not have bought? must she not have bought? must we not have bought? must you not have bought? must they not have bought?	must I not have been buying? must you not have been buying? must she not have been buying? must we not have been buying? must you not have been buying? must they not have been buying?