I could check you could check she could check we could check you could check they could check
Forme en V-ing
I could be checking you could be checking she could be checking we could be checking you could be checking they could be checking
Perfect
I could have checked you could have checked she could have checked we could have checked you could have checked they could have checked
Perfect en V-ing
I could have been checking you could have been checking she could have been checking we could have been checking you could have been checking they could have been checking
Négation
Forme simple
I could not check you could not check she could not check we could not check you could not check they could not check
Forme en V-ing
I could not be checking you could not be checking she could not be checking we could not be checking you could not be checking they could not be checking
Perfect
I could not have checked you could not have checked she could not have checked we could not have checked you could not have checked they could not have checked
Perfect en V-ing
I could not have been checking you could not have been checking she could not have been checking we could not have been checking you could not have been checking they could not have been checking
Forme interrogative
Forme simple
could I check? could you check? could she check? could we check? could you check? could they check?
Forme en V-ing
could I be checking? could you be checking? could she be checking? could we be checking? could you be checking? could they be checking?
Perfect
could I have checked? could you have checked? could she have checked? could we have checked? could you have checked? could they have checked?
Perfect en V-ing
could I have been checking? could you have been checking? could she have been checking? could we have been checking? could you have been checking? could they have been checking?
Forme interro-négative
Forme simple
could I not check? could you not check? could she not check? could we not check? could you not check? could they not check?
Forme en V-ing
could I not be checking? could you not be checking? could she not be checking? could we not be checking? could you not be checking? could they not be checking?
Perfect
could I not have checked? could you not have checked? could she not have checked? could we not have checked? could you not have checked? could they not have checked?
Perfect en V-ing
could I not have been checking? could you not have been checking? could she not have been checking? could we not have been checking? could you not have been checking? could they not have been checking?