English verb conjugation
MUST CRIB

Regular verb: crib - cribbed - cribbed

Affirmation

Simple form	V-ing form
I must crib you must crib he must crib we must crib you must crib they must crib	I must be cribbing you must be cribbing he must be cribbing we must be cribbing you must be cribbing they must be cribbing
Perfect	V-ing perfect
I must have cribbed you must have cribbed he must have cribbed we must have cribbed you must have cribbed they must have cribbed	I must have been cribbing you must have been cribbing he must have been cribbing we must have been cribbing you must have been cribbing they must have been cribbing

Negation

Simple form	V-ing form
I must not crib you must not crib he must not crib we must not crib you must not crib they must not crib	I must not be cribbing you must not be cribbing he must not be cribbing we must not be cribbing you must not be cribbing they must not be cribbing
Perfect	V-ing perfect
I must not have cribbed you must not have cribbed he must not have cribbed we must not have cribbed you must not have cribbed they must not have cribbed	I must not have been cribbing you must not have been cribbing he must not have been cribbing we must not have been cribbing you must not have been cribbing they must not have been cribbing

Interrogative form

Simple form	V-ing form
must I crib? must you crib? must he crib? must we crib? must you crib? must they crib?	must I be cribbing? must you be cribbing? must he be cribbing? must we be cribbing? must you be cribbing? must they be cribbing?
Perfect	V-ing perfect
must I have cribbed? must you have cribbed? must he have cribbed? must we have cribbed? must you have cribbed? must they have cribbed?	must I have been cribbing? must you have been cribbing? must he have been cribbing? must we have been cribbing? must you have been cribbing? must they have been cribbing?

Interro-negative form

Simple form	V-ing form
must I not crib? must you not crib? must he not crib? must we not crib? must you not crib? must they not crib?	must I not be cribbing? must you not be cribbing? must he not be cribbing? must we not be cribbing? must you not be cribbing? must they not be cribbing?
Perfect	V-ing perfect
must I not have cribbed? must you not have cribbed? must he not have cribbed? must we not have cribbed? must you not have cribbed? must they not have cribbed?	must I not have been cribbing? must you not have been cribbing? must he not have been cribbing? must we not have been cribbing? must you not have been cribbing? must they not have been cribbing?