English verb conjugation
MUST CROAK

Regular verb: croak - croaked - croaked

Affirmation

Simple form	V-ing form
I must croak you must croak he must croak we must croak you must croak they must croak	I must be croaking you must be croaking he must be croaking we must be croaking you must be croaking they must be croaking
Perfect	V-ing perfect
I must have croaked you must have croaked he must have croaked we must have croaked you must have croaked they must have croaked	I must have been croaking you must have been croaking he must have been croaking we must have been croaking you must have been croaking they must have been croaking

Negation

Simple form	V-ing form
I mustn't croak you mustn't croak he mustn't croak we mustn't croak you mustn't croak they mustn't croak	I mustn't be croaking you mustn't be croaking he mustn't be croaking we mustn't be croaking you mustn't be croaking they mustn't be croaking
Perfect	V-ing perfect
I mustn't have croaked you mustn't have croaked he mustn't have croaked we mustn't have croaked you mustn't have croaked they mustn't have croaked	I mustn't have been croaking you mustn't have been croaking he mustn't have been croaking we mustn't have been croaking you mustn't have been croaking they mustn't have been croaking

Interrogative form

Simple form	V-ing form
must I croak? must you croak? must he croak? must we croak? must you croak? must they croak?	must I be croaking? must you be croaking? must he be croaking? must we be croaking? must you be croaking? must they be croaking?
Perfect	V-ing perfect
must I have croaked? must you have croaked? must he have croaked? must we have croaked? must you have croaked? must they have croaked?	must I have been croaking? must you have been croaking? must he have been croaking? must we have been croaking? must you have been croaking? must they have been croaking?

Interro-negative form

Simple form	V-ing form
mustn't I croak? mustn't you croak? mustn't he croak? mustn't we croak? mustn't you croak? mustn't they croak?	mustn't I be croaking? mustn't you be croaking? mustn't he be croaking? mustn't we be croaking? mustn't you be croaking? mustn't they be croaking?
Perfect	V-ing perfect
mustn't I have croaked? mustn't you have croaked? mustn't he have croaked? mustn't we have croaked? mustn't you have croaked? mustn't they have croaked?	mustn't I have been croaking? mustn't you have been croaking? mustn't he have been croaking? mustn't we have been croaking? mustn't you have been croaking? mustn't they have been croaking?