must concertina
Regular verb: concertina - concertinaed- concertinaed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must concertina
you must concertina
he must concertina
we must concertina
you must concertina
they must concertina 	I must be concertinaing
you must be concertinaing
he must be concertinaing
we must be concertinaing
you must be concertinaing
they must be concertinaing	I must have concertinaed
you must have concertinaed
he must have concertinaed
we must have concertinaed
you must have concertinaed
they must have concertinaed	I must have been concertinaing
you must have been concertinaing
he must have been concertinaing
we must have been concertinaing
you must have been concertinaing
they must have been concertinaing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not concertina
you must not concertina
he must not concertina
we must not concertina
you must not concertina
they must not concertina 	I must not be concertinaing
you must not be concertinaing
he must not be concertinaing
we must not be concertinaing
you must not be concertinaing
they must not be concertinaing	I must not have concertinaed
you must not have concertinaed
he must not have concertinaed
we must not have concertinaed
you must not have concertinaed
they must not have concertinaed	I must not have been concertinaing
you must not have been concertinaing
he must not have been concertinaing
we must not have been concertinaing
you must not have been concertinaing
they must not have been concertinaing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I concertina?
must you concertina?
must he concertina?
must we concertina?
must you concertina?
must they concertina? 	must I be concertinaing?
must you be concertinaing?
must he be concertinaing?
must we be concertinaing?
must you be concertinaing?
must they be concertinaing? 	must I have concertinaed?
must you have concertinaed?
must he have concertinaed?
must we have concertinaed?
must you have concertinaed?
must they have concertinaed? 	must I have been concertinaing?
must you have been concertinaing?
must he have been concertinaing?
must we have been concertinaing?
must you have been concertinaing?
must they have been concertinaing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not concertina?
must you not concertina?
must he not concertina?
must we not concertina?
must you not concertina?
must they not concertina? 	must I not be concertinaing?
must you not be concertinaing?
must he not be concertinaing?
must we not be concertinaing?
must you not be concertinaing?
must they not be concertinaing? 	must I not have concertinaed?
must you not have concertinaed?
must he not have concertinaed?
must we not have concertinaed?
must you not have concertinaed?
must they not have concertinaed? 	must I not have been concertinaing?
must you not have been concertinaing?
must he not have been concertinaing?
must we not have been concertinaing?
must you not have been concertinaing?
must they not have been concertinaing?