must keen
Regular verb: keen - keened- keened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must keen
you must keen
he must keen
we must keen
you must keen
they must keen 	I must be keening
you must be keening
he must be keening
we must be keening
you must be keening
they must be keening	I must have keened
you must have keened
he must have keened
we must have keened
you must have keened
they must have keened	I must have been keening
you must have been keening
he must have been keening
we must have been keening
you must have been keening
they must have been keening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't keen
you mustn't keen
he mustn't keen
we mustn't keen
you mustn't keen
they mustn't keen 	I mustn't be keening
you mustn't be keening
he mustn't be keening
we mustn't be keening
you mustn't be keening
they mustn't be keening	I mustn't have keened
you mustn't have keened
he mustn't have keened
we mustn't have keened
you mustn't have keened
they mustn't have keened	I mustn't have been keening
you mustn't have been keening
he mustn't have been keening
we mustn't have been keening
you mustn't have been keening
they mustn't have been keening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I keen?
must you keen?
must he keen?
must we keen?
must you keen?
must they keen? 	must I be keening?
must you be keening?
must he be keening?
must we be keening?
must you be keening?
must they be keening? 	must I have keened?
must you have keened?
must he have keened?
must we have keened?
must you have keened?
must they have keened? 	must I have been keening?
must you have been keening?
must he have been keening?
must we have been keening?
must you have been keening?
must they have been keening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I keen?
mustn't you keen?
mustn't he keen?
mustn't we keen?
mustn't you keen?
mustn't they keen? 	mustn't I be keening?
mustn't you be keening?
mustn't he be keening?
mustn't we be keening?
mustn't you be keening?
mustn't they be keening? 	mustn't I have keened?
mustn't you have keened?
mustn't he have keened?
mustn't we have keened?
mustn't you have keened?
mustn't they have keened? 	mustn't I have been keening?
mustn't you have been keening?
mustn't he have been keening?
mustn't we have been keening?
mustn't you have been keening?
mustn't they have been keening?