I can concertina you can concertina she can concertina we can concertina you can concertina they can concertina
V-ing form
I can be concertinaing you can be concertinaing she can be concertinaing we can be concertinaing you can be concertinaing they can be concertinaing
Perfect
I can have concertinaed you can have concertinaed she can have concertinaed we can have concertinaed you can have concertinaed they can have concertinaed
V-ing perfect
I can have been concertinaing you can have been concertinaing she can have been concertinaing we can have been concertinaing you can have been concertinaing they can have been concertinaing
Negation
Simple form
I cannot concertina you cannot concertina she cannot concertina we cannot concertina you cannot concertina they cannot concertina
V-ing form
I cannot be concertinaing you cannot be concertinaing she cannot be concertinaing we cannot be concertinaing you cannot be concertinaing they cannot be concertinaing
Perfect
I cannot have concertinaed you cannot have concertinaed she cannot have concertinaed we cannot have concertinaed you cannot have concertinaed they cannot have concertinaed
V-ing perfect
I cannot have been concertinaing you cannot have been concertinaing she cannot have been concertinaing we cannot have been concertinaing you cannot have been concertinaing they cannot have been concertinaing
Interrogative form
Simple form
can I concertina? can you concertina? can she concertina? can we concertina? can you concertina? can they concertina?
V-ing form
can I be concertinaing? can you be concertinaing? can she be concertinaing? can we be concertinaing? can you be concertinaing? can they be concertinaing?
Perfect
can I have concertinaed? can you have concertinaed? can she have concertinaed? can we have concertinaed? can you have concertinaed? can they have concertinaed?
V-ing perfect
can I have been concertinaing? can you have been concertinaing? can she have been concertinaing? can we have been concertinaing? can you have been concertinaing? can they have been concertinaing?
Interro-negative form
Simple form
can I not concertina? can you not concertina? can she not concertina? can we not concertina? can you not concertina? can they not concertina?
V-ing form
can I not be concertinaing? can you not be concertinaing? can she not be concertinaing? can we not be concertinaing? can you not be concertinaing? can they not be concertinaing?
Perfect
can I not have concertinaed? can you not have concertinaed? can she not have concertinaed? can we not have concertinaed? can you not have concertinaed? can they not have concertinaed?
V-ing perfect
can I not have been concertinaing? can you not have been concertinaing? can she not have been concertinaing? can we not have been concertinaing? can you not have been concertinaing? can they not have been concertinaing?