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 mustn't crib you mustn't crib he mustn't crib we mustn't crib you mustn't crib they mustn't crib	I mustn't be cribbing you mustn't be cribbing he mustn't be cribbing we mustn't be cribbing you mustn't be cribbing they mustn't be cribbing
Perfect	V-ing perfect
I mustn't have cribbed you mustn't have cribbed he mustn't have cribbed we mustn't have cribbed you mustn't have cribbed they mustn't have cribbed	I mustn't have been cribbing you mustn't have been cribbing he mustn't have been cribbing we mustn't have been cribbing you mustn't have been cribbing they mustn't 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
mustn't I crib? mustn't you crib? mustn't he crib? mustn't we crib? mustn't you crib? mustn't they crib?	mustn't I be cribbing? mustn't you be cribbing? mustn't he be cribbing? mustn't we be cribbing? mustn't you be cribbing? mustn't they be cribbing?
Perfect	V-ing perfect
mustn't I have cribbed? mustn't you have cribbed? mustn't he have cribbed? mustn't we have cribbed? mustn't you have cribbed? mustn't they have cribbed?	mustn't I have been cribbing? mustn't you have been cribbing? mustn't he have been cribbing? mustn't we have been cribbing? mustn't you have been cribbing? mustn't they have been cribbing?