Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I must buy buy you must buy buy he must buy buy we must buy buy you must buy buy they must buy buy
V-ing form
I must be buy buying you must be buy buying he must be buy buying we must be buy buying you must be buy buying they must be buy buying
Perfect
I must have buy buyed you must have buy buyed he must have buy buyed we must have buy buyed you must have buy buyed they must have buy buyed
V-ing perfect
I must have been buy buying you must have been buy buying he must have been buy buying we must have been buy buying you must have been buy buying they must have been buy buying
Negation
Simple form
I must not buy buy you must not buy buy he must not buy buy we must not buy buy you must not buy buy they must not buy buy
V-ing form
I must not be buy buying you must not be buy buying he must not be buy buying we must not be buy buying you must not be buy buying they must not be buy buying
Perfect
I must not have buy buyed you must not have buy buyed he must not have buy buyed we must not have buy buyed you must not have buy buyed they must not have buy buyed
V-ing perfect
I must not have been buy buying you must not have been buy buying he must not have been buy buying we must not have been buy buying you must not have been buy buying they must not have been buy buying
Interrogative form
Simple form
must I buy buy? must you buy buy? must he buy buy? must we buy buy? must you buy buy? must they buy buy?
V-ing form
must I be buy buying? must you be buy buying? must he be buy buying? must we be buy buying? must you be buy buying? must they be buy buying?
Perfect
must I have buy buyed? must you have buy buyed? must he have buy buyed? must we have buy buyed? must you have buy buyed? must they have buy buyed?
V-ing perfect
must I have been buy buying? must you have been buy buying? must he have been buy buying? must we have been buy buying? must you have been buy buying? must they have been buy buying?
Interro-negative form
Simple form
must I not buy buy? must you not buy buy? must he not buy buy? must we not buy buy? must you not buy buy? must they not buy buy?
V-ing form
must I not be buy buying? must you not be buy buying? must he not be buy buying? must we not be buy buying? must you not be buy buying? must they not be buy buying?
Perfect
must I not have buy buyed? must you not have buy buyed? must he not have buy buyed? must we not have buy buyed? must you not have buy buyed? must they not have buy buyed?
V-ing perfect
must I not have been buy buying? must you not have been buy buying? must he not have been buy buying? must we not have been buy buying? must you not have been buy buying? must they not have been buy buying?