could concertina
Regular verb: concertina - concertinaed- concertinaed

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

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't concertina
you couldn't concertina
she couldn't concertina
we couldn't concertina
you couldn't concertina
they couldn't concertina 	I couldn't be concertinaing
you couldn't be concertinaing
she couldn't be concertinaing
we couldn't be concertinaing
you couldn't be concertinaing
they couldn't be concertinaing	I couldn't have concertinaed
you couldn't have concertinaed
she couldn't have concertinaed
we couldn't have concertinaed
you couldn't have concertinaed
they couldn't have concertinaed	I couldn't have been concertinaing
you couldn't have been concertinaing
she couldn't have been concertinaing
we couldn't have been concertinaing
you couldn't have been concertinaing
they couldn't have been concertinaing	

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

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I concertina?
couldn't you concertina?
couldn't she concertina?
couldn't we concertina?
couldn't you concertina?
couldn't they concertina? 	couldn't I be concertinaing?
couldn't you be concertinaing?
couldn't she be concertinaing?
couldn't we be concertinaing?
couldn't you be concertinaing?
couldn't they be concertinaing? 	couldn't I have concertinaed?
couldn't you have concertinaed?
couldn't she have concertinaed?
couldn't we have concertinaed?
couldn't you have concertinaed?
couldn't they have concertinaed? 	couldn't I have been concertinaing?
couldn't you have been concertinaing?
couldn't she have been concertinaing?
couldn't we have been concertinaing?
couldn't you have been concertinaing?
couldn't they have been concertinaing?