I can concern you can concern he can concern we can concern you can concern they can concern
Forma con V-ing
I can be concerning you can be concerning he can be concerning we can be concerning you can be concerning they can be concerning
Perfecto
I can have concerned you can have concerned he can have concerned we can have concerned you can have concerned they can have concerned
Perfecto con V-ing
I can have been concerning you can have been concerning he can have been concerning we can have been concerning you can have been concerning they can have been concerning
Negación
Forma simple
I cannot concern you cannot concern he cannot concern we cannot concern you cannot concern they cannot concern
Forma con V-ing
I cannot be concerning you cannot be concerning he cannot be concerning we cannot be concerning you cannot be concerning they cannot be concerning
Perfecto
I cannot have concerned you cannot have concerned he cannot have concerned we cannot have concerned you cannot have concerned they cannot have concerned
Perfecto con V-ing
I cannot have been concerning you cannot have been concerning he cannot have been concerning we cannot have been concerning you cannot have been concerning they cannot have been concerning
Forma interrogativa
Forma simple
can I concern? can you concern? can he concern? can we concern? can you concern? can they concern?
Forma con V-ing
can I be concerning? can you be concerning? can he be concerning? can we be concerning? can you be concerning? can they be concerning?
Perfecto
can I have concerned? can you have concerned? can he have concerned? can we have concerned? can you have concerned? can they have concerned?
Perfecto con V-ing
can I have been concerning? can you have been concerning? can he have been concerning? can we have been concerning? can you have been concerning? can they have been concerning?
Forma interro-negativa
Forma simple
can I not concern? can you not concern? can he not concern? can we not concern? can you not concern? can they not concern?
Forma con V-ing
can I not be concerning? can you not be concerning? can he not be concerning? can we not be concerning? can you not be concerning? can they not be concerning?
Perfecto
can I not have concerned? can you not have concerned? can he not have concerned? can we not have concerned? can you not have concerned? can they not have concerned?
Perfecto con V-ing
can I not have been concerning? can you not have been concerning? can he not have been concerning? can we not have been concerning? can you not have been concerning? can they not have been concerning?